SI-7776 post-erasure signature clashes are now macro-aware

"double definition: macro this and method that have same type after erasure"
This error doesn't make sense when macros are involved, because macros
expand at compile-time, where we're not affected by erasure. Moreover,
macros produce no bytecode, which means that we're safe from VerifyErrors.
Enforce consistency of pack, docs, osgi, maven tasks.

Instead of scattering properties all over invocations of
staged-docs, staged-pack, make-bundle, copy-bundle and mvn-package,
these are now all fully determined by the project they act on.

The varying arguments to these macros are all centralized.
They are named like `project.prop`, where `prop` is one of:
description, package, dir, name, namesuffix, version,
targetdir, targetjar, jar, docroot, skipPackage, srcdir, src, srcjar.

The defaults for these properties are computed using `init-project-prop`.
De-duplicate logic in maven deployment.
Render relevant properties to buildcharacter.properties
Collections library tidying and deprecation.  Separate parts are listed below.

Collections library tidying, part one: scripting.

Everything in scala.collection.scripting is deprecated now, along with the
<< method that is implemented in a few other classes.  Scripting does not
seem used at all, and anyone who did can easily write a wrapper that does
the same thing.

Deprecated *Proxy collections.

The only place proxies were used in the library was in swing.ListView, and
that was easy to change to a lazy val.

Proxy itself is used in ScalaNumberProxy and such, so it was left
undeprecated.

Deprecated Synchronized* traits from collections.

Synchronizability does not compose well, and it requires careful examination
of every method (which has not actually been done).

Places where the Scala codebase needs to be fixed (eventually) include:
  scala.reflect.internal.util.Statistics$QuantMap
  scala.tools.nsc.interactive.Global (several places)

Deprecated LinkedList (including Double- and -Like variants).

Interface is idiosyncratic and dangerously low-level.  Although some
low-level functionality of this sort would be useful, this doesn't seem
to be the ideal implementation.

Also deprecated the extractFirst method in Queue as it exposes LinkedList.
Cannot shift internal representations away from LinkedList at this time
because of that method.

Deprecated non-finality of several toX collection methods.

Improved documentation of most toX collection methods to describe what the
expectation is for their behavior.  Additionally deprecated overriding of
  - toIterator in IterableLike (should always forward to iterator)
  - toTraversable in TraversableLike (should always return self)
  - toIndexedSeq in immutable.IndexedSeq (should always return self)
  - toMap in immutable.Map (should always return self)
  - toSet in immutable.Set (should always return self)

Did not do anything with IterableLike.toIterable or Seq/SeqLike.toSeq since
for some odd reason immutable.Range overrides those.

Deprecated Forwarders from collections.

Forwarding, without an automatic mechanism to keep up to date with changes
in the forwarded class, is inherently unreliable.  Absent a mechanism to
keep current, they're deprecated.  ListBuffer is the only class in the
collections library that uses forwarders, and that functionality can be
rolled into ListBuffer itself.

Deprecating immutable set/map adaptors.

They're a bad idea (barring compiler support) for the same reason that all
the other adaptors are a bad idea: they get out of date and probably have a
variety of performance bugs.

Deprecated inheritance from leaf classes in immutable collections.

Inheriting from leaf-classes in immutable collections is rarely a good idea
since whenever you use any interesting collections method you'll revert to
the original class.  Also, the methods are often designed to work with only
particular behavior, and an override would be difficult (at best) to make
work.  Fortunately, people seem to have realized this and there are few to
no cases of people extending PagedSeq and TreeSet and the like.

Note that in many cases the classes will become sealed not final.

Deprecated overriding of methods and inheritance from various mutable
collections.

Some mutable collections seem unsuited for overriding since to override
anything interesting you would need vast knowledge of internal data
structures and/or access to private methods.  These include
  - ArrayBuilder.ofX classes.
  - ArrayOps
  - Some methods of BitSet (moved others from private to protected final)
  - Some methods of HashTable and FlatHashTable
  - Some methods of HashMap and HashSet (esp += and -= which just forward)
  - Some methods of other maps and sets (LinkedHashX, ListMap, TreeSet)
  - PriorityQueue
  - UnrolledBuffer

This is a somewhat aggressive deprecation, the theory being better to try it
out now and back off if it's too much than not attempt the change and be
stuck with collections that can neither be safely inherited nor have
implementation details changed.

Note that I have made no changes--in this commit--which would cause
deprecation warnings in any of the Scala projects available on Maven (at
least as gathered by Adriaan).  There are deprecation warnings induced
within the library (esp. for classes/traits that should become static) and
the compiler.  I have not attempted to fix all the deprecations in the
compiler as some of them touch the IDE API (but these mostly involved
Synchronized which is inherently unsafe, so this should be fixed
eventually in coordination with the IDE code base(s)).

Updated test checks to include new deprecations.

Used a higher level implementation for messages in JavapClass.
Extra repository hook via `extra.repo.url` var

Previously defaulted to 'https://oss.sonatype.org/content/repositories/releases',
now must be set manually. PR validation uses it to configure the repository
that has the artifacts published during validation.
More useful ant targets for faster pr validation
IDE needs actors/swing/continuations publish for validation.

As soon as they are also modularized, we can go back to
only building/publishing the core (lib/reflect/compiler).
Fast path for ByNameClass in isImpossibleSubtype

These show up often due to the way that searches for
implicit views operate: firstly `A=>B` is sought, and
failing that `(=>A) => B`.
Cache ImplicitInfo#isCyclicOrErroneous

An optimization in implicit search.

ImplicitInfo-s themselves are cached (per-run) in Contexts
(for in-scope implicits) and in Implicits (for companion object
implicits.)
Add a per-run cache for member symbols

We are all used to calls to `definitions.PredefModule`, or
`defintions.Predef_???` to grab the symbol of some well known
entity. But you'll notice that some of these are lazy vals,
and others are defs.

Why is this so? In the presentation compiler, a member like
`Predef.???` will be assigned a new symbol after the user
browses into `Predef.scala`.

Mistakenly using vals in definitions leads to subtle
IDE bugs like SI-7678. We are able to trigger these
situations in tests, as noted in the comments of that issue.

Changing the vals to defs, on the other hand, has a performance
penalty. Some schemes to workaround this have shown up:
cache them per-implicit search, or compare method names and owners
rather than symbols on hot paths in the type checker.

This commit introduces a facility to cache these sort of symbols
per-run, and uses it to check for `Predef.conforms` and
and for the class/type tag materializers.

A followup pull request (WIP: https://github.com/retronym/scala/compare/ticket/7678-2)
will expand the use of to address the widespread and unsafe caching
of member symbols that I found while investigating SI-7678.
SI-7678 Don't cache member symbols of TypeTags in Definitions.

It we can only safely use vals in Definitions for top-level symbols.
Otherwise, when the IDE switches to loading the symbol from source,
we can hold on to a stale symbol, which in turn impedes implicit
materialization of TypeTags.

This commit moves (most) of the accessors for member symbols
into RunDefinitions, and changes calling code accordingly.
This is a win for presentation compiler correctness, and
might even shave of a few cycles.

In a few cases, I have had to leave a `def` to a member symbol
in Definitions so we can get to it from the SymbolTable cake,
which doesn't see RunDefinitions.

The macro FastTrack facility now correctly recreates the mapping
from Symbol to macro implementation each run, using a new facility
in perRunCaches to create a run-indexed cache.

The enclosed test recreates the situation reported in the ticket,
in which TypeTags.scala is loaded from source.
Merge pull request #3101 from xeno-by/ticket/7776

SI-7776 post-erasure signature clashes are now macro-aware
Merge pull request #3092 from retronym/ticket/7678-2

Small implicit optimizations, and SI-7678 RunDefinitions
Avoid needless TypeRef allocation during erasure.

  - ThisType(some.package) need not be erased, we can let
    that prefix through unchanged and avoid churning through
    allocations.
  - Sharpen the condition in `rebindInnerClass`. The answer
    to the deleted comment in the code, is "anonymous and
    local classes", which are specifically excluded in the
    new formulation.
  - Finally, detect if erasure of the TypeRef is an identity and reuse
    the original.

Waste not, want not.

To expand on the first point, here is what used to happen during
erasure:

    scala> val scalaPack = typeOf[Predef.type].prefix
    scalaPack: $r.intp.global.Type = scala.type

    scala> typeDeconstruct.show(scalaPack)
    res19: String = ThisType(package scala)

    scala> typeDeconstruct.show(erasure.scalaErasure(scalaPack))
    res20: String = TypeRef(TypeSymbol(final class scala extends ))

Showing one step of the erasure type map:

    scala> typeDeconstruct.show(scalaPack.asInstanceOf[SubType].underlying.typeOfThis)
    res21: String = SingleType(pre = ThisType(package <root>), package scala)
Address review comments

  - anonymize unused pattern binder
  - avoid negations
Merge pull request #3103 from Ichoran/topic/tidy-collections

Topic/tidy collections
Merge pull request #3094 from retronym/topic/erasure-opt

Avoid needless TypeRef allocation during erasure.
Merge pull request #3108 from adriaanm/faster-build

Faster PR validation