SI-7410 REPL uses improved tools.jar locator

The logic in partest for snooping around for tools.jar
is moved to PathResolver, and ILoop uses it from there.

If JAVA_HOME is toolless, check out java.home.

The use case was that Ubuntu installs with `java` at
version 6 and `javac` at version 7; it's easy to wind
up with JAVA_HOME pointing at the version 6 JRE, as
I discovered.  It's confusing when that happens.

In future, partest might run under 7 and fork tests
under 6, but those permutations are downstream.
PathResolver uses platform EOL to mkStrings
Avoid caching different types in TypeSymbol.

Try to prevent TypeSymbols from caching a different typeref
for tpe_* and typeConstructor if the symbol is monomorphic.
I find this undesirable:

  scala> AnyRefClass.tpe eq AnyRefClass.typeConstructor
  res0: Boolean = true

  scala> AnyRefClass.tpe eq AnyRefClass.typeConstructor
  res1: Boolean = false
Concision contribution.

We have lots of core classes for which we need not go through
the symbol to get the type:

  ObjectClass.tpe -> ObjectTpe
  AnyClass.tpe    -> AnyTpe

I updated everything to use the concise/direct version,
and eliminated a bunch of noise where places were calling
typeConstructor, erasedTypeRef, and other different-seeming methods
only to always wind up with the same type they would have received
from sym.tpe. There's only one Object type, before or after erasure,
with or without type arguments.

Calls to typeConstructor were especially damaging because (see
previous commit) it had a tendency to cache a different type than
the type one would find via other means. The two types would
compare =:=, but possibly not == and definitely not eq. (I still
don't understand what == is expected to do with types.)
A couple additional simplifications.

As noted by reviewer.
SI-7287 include all compiler sources in -src.jar
SI-7003 Partest redirects stderr to log file

Some scalac output is on stderr, and it's useful to see that
in the log file, especially for debugging.

Adds a line filter for logs, specified as "filter: pattern"
in the test source.

Backslashes are made forward only when detected as paths.

Test alignments:

Deprecations which do not pertain to the system under test
are corrected in the obvious way.

When testing deprecated API, suppress warnings by deprecating
the Test object.

Check files are updated with useful true warnings, instead of
running under -nowarn.

Language feature imports as required, instead of running under -language.

Language feature not required, such as casual use of postfix.

Heed useful warning.

Ignore broken warnings. (Rarely, -nowarn.)

Inliner warnings pop up under -optimise only, so for now, just
filter them out where they occur.

Debug output from the test required an update.
SI-7198 Par-Test uses filters files

Partest will also read files/filters and files/kind/filters for
filter expressions (one per line, trimmed, leading #comments)
which are taken as regexes.

A test/files/filters is provided which attempts to quell HotSpot
warnings; the test for this commit requires it.

The elided lines can be revealed using the lemon juice of verbosity:

apm@mara:~/projects/snytt/test$ ./partest --verbose --show-diff files/run/t7198.scala
[snip]
>>>>> Transcripts from failed tests >>>>>

> partest files/run/t7198.scala
% scalac t7198.scala
[snip]
% filtering t7198-run.log
--Over the moon
--Java HotSpot(TM) 64-Bit Server VM warning: Failed to reserve shared memory (errno = 28).

The filtering operation is part of the transcript, which is printed on failure.

No attempt is made to be clever about not slurping the filters file a thousand times.

Previous literal patterns had to be updated because there's parens in them thar strings.

Future feature: pattern aliases, define once globally and invoke in test filters.
Merge pull request #2585 from paulp/pr/concision-contribution

Concision contribution.
Merge pull request #2594 from adriaanm/ticket-7287

SI-7287 include all compiler sources in -src.jar
Merge pull request #2591 from som-snytt/topic/partest-inches

SI-7003 Partest redirects stderr to log file
Merge pull request #2584 from som-snytt/issue/repl-tools-jar

SI-7410 REPL uses improved tools.jar locator