SI-7622 Phase assembly is testable

Fixing hash on nodes makes fault detection deterministic,
which aids testing.

Error messages are shortened and .dot files are dumped
automatically on faults to guard against future flakiness.
SI-7622 -Xgenerate-phase-graph is an info option

-Xgenerate-phase-graph is comparable to -Xshow-phases.

The knowledge about what is an info-only option is refactored
to Settings, which also knows which group of options comprise
the optimiser set.
SI-7622 Phases are enabled or not

Refactor the calculation of the "phase chain" a bit.
In particular, initial and terminal phases are not special
except that they must be head and last.

When done, filter for enabled phases. At this commit,
nobody claims to be disabled.

Additional sanity support of phases settings.
SI-7622 -Xshow-phases can show disabled phases

With -Ydebug, -Xshow-phases will show phases that are skipped
or not enabled.

The code is slightly refactored, so the flags table will also benefit.
SI-7622 Plugins can be not enabled

Plugins can interrogate options and declare themselves not
enabled.  The plugin itself can return false from its init
if the options do not compute.  A plugin phase component
can declare itself not enabled, same as an internal phase.

No one exploits this facility at this commit.
SI-7622 Clean Up Phase Assembly

Let optimiser components and continuations plugin opt-out
when required flags are not set.

Wasted time on a whitespace error in check file, so let
--debug dump the processed check file and its diff.
SI-7622 Scaladoc and error message polish

Restores the verbiage "run right after".
Merge branch '2.10.2' into 2.10.3

Conflicts:
	src/compiler/scala/tools/nsc/typechecker/NamesDefaults.scala
Merge pull request #2878 from JamesIry/2.10.3

Merge 2.10.2 into 2.10.3
update typesafe.artifactory-online.com to private-repo
Change Scala license to unmodified 3-clause BSD.

No longer using the slightly reworded 3-clause BSD license.
This does not change the meaning of the license,
just aligns it with the standard wording.
SI-7801 Fix a nightmarish bug in Symbols#adaptInfos

The compiler-in-residence has always been a sketchy affair;
FSC and REPL offers a bounty of bugs that exploit the menagerie
of time-travel mechanisms in play for symbols' metadata (type, flags,
name and owner.) but are often cleverly masked by optimizations in
the compiler based on reference equality.

The latest: an innocuous change in Erasure:

  https://github.com/scala/scala/commit/d8b96bb8#commitcomment-3995163

means that some `ErasureMap`-s over `MethodType`-s are now true
identities (as `UnitTpe` is always the same object, whereas
`erasedTypeRef(UnitClass)` returns an different `TypeRef` each
time.)

This, in turn, enables `TypeMap#mapOver` to reuse
the existing enclosing type, and so on. On such subtleties hinge
further optimizations, such as whether or not a given phase's
`InfoTransformer` needs to add an entry in a symbols type history.

When the REPL (or FSC / Presentation Compiler) creates a new
`Run`, `Symbol#rawInfo` tries to adapt the entries in the type
history for the new run. For packages, this was taken to be a
no-op; each entry is marked as being valid in the new run and
no further action is taken. This logic lurks in `adaptInfos`.

But, when the namer enters a new symbol in a package, it
*mutates* the Scope of that package classes info `enteringTyper`.
So the later entries in the type history *must* be invalidated
and recomputed.

We have two choices for a fix:

 1) modify `Namers#enterInScope` to blow away the subsequent
    type history for the owning symbol after inserting the
    new member. Something like `owner.setInfo(owner.info)` would
    have the desired effect.
 2) Change `adaptInfos` to be more conservative when it comes
    to package classes, and retain only the oldest entry in the
    type history.

This commit goes for option 2.
Merge remote-tracking branch 'origin/2.10.x' into merge/2.10.x-to-2.10.3
SI-7815 Dealias before deeming method type as dependent

To enable eta-expansion of method types seen from a prefix that
renders the result type as independent from the parameter symbols.

The enclosed test shows that we dealias types before checking
dependence, and that we do this deeply (e.g. type arguments are
also dealised.)

An existing test, neg/error_dependentMethodTpeConversionToFunction,
confirms that bona-fide dependent methods are still prohibited from
eta expansion.
SI-7825 Consider DEFAULTMETHOD when refchecking concreteness

A class should not be required to implement a Java default method.

This commit uses `isDeferredNotDefault` in place of `isDeferred`
when finding unimplemented methods.

The test itself does not depend on Java 8 as we use scalac's
Java source parser to set things up.
SI-7398 Enable test for Java 8 source parser under Java 8

There is no need to skip it as it only depends on our changes
to our JavaParser, and not on any bytecode features of Java 8.
SI-6701 add SYNTHETIC flag to the reflection api
SI-7304 improve deprecation warnings for tree factory methods
Merge pull request #2923 from retronym/ticket/7825

SI-7825 Consider DEFAULTMETHOD when refchecking concreteness
Merge pull request #2882 from adriaanm/license-cleanup-2.10.x

Change Scala license to unmodified 3-clause BSD.