Made the Launchable Property tester use the presentation compiler.

This makes the Debug As/Run As menus much faster. It was not uncommon to wait for many
seconds when hovering over those menus. Added a bunch of tests as well.

Fixed #100818, #100082 along the way.
Remove the JUnitTester from the source code.
Removed stray `println`, added some comments and extracted helper methods.
Made `problemsOf` public, so it can be used from the worksheet.

Added helper method for handling responses.
More abstract dealings with Scala compilation units. 

We need a way to treat uniformly different kinds of Scala-based sources. Until now
we routed everything through `ScalaCompilationUnit`, that extends the JDT `CompilationUnit`
class. This tight connection is counter-productive, and in most cases, unnecessary.

This commit is a step towards extracting a set of interfaces for other Scala-based
sources to benefit of reconciliation ('errors-as-you-type'), hyperlinking and completion
engine that already exists.

* extracted `InteractiveCompilationUnit` as a super type of `ScalaCompilationUnit`
* switched from `ScalaCompilationUnit` to `InteractiveCompilationUnit` wherever possible, to allow
hyperlinking to work in the scala-worksheet project
* added a utility method to retrieve the compilation unit associated with an open editor that
uses the platform adapter protocol to allow other plugins to participate.
Add 'additionalCpEntries' to the Sbt builder.

This allows the worksheet to use the builder in order to compiler worksheets, 
without polluting the project class path.
Allow completions from different source files than `ScalaSourceFile`.

Added an interface for editors that can expose the `SourceViewer`.
Removed the release-build-2.9.sh script

After the major rewrite of our maven build
(SHA-bfc88fd04d80d68760e43dbe60b638c314280f0d), the `release-build-ide-29.sh`
is henceforth useless (and worse, it's not even working anymore because the
`release-ide-29` maven profile does no longer exist in the POMs).

Now, to build the IDE (for instance, for Scala 2.10.0-M6), the following plain
maven  command is enough:

> ./build-all.sh -Dscala.version=2.10.0-M6 -Drepo.scala-refactoring=http://download.scala-ide.org/incoming-release-210/dependencies/scala-refactoring -Drepo.scalariform=http://download.scala-ide.org/incoming-release-210/dependencies/scalariform -Dversion.tag=m2 -Pscala-2.10.x clean install

Note that the above command assumes that you have produced the p2 repository
for both our dependencies (scalariform and scala-refactoring).
Insert Java parameter names in method completions.

Fixed #1001183.
Return an option when looking for an `InteractiveCompilationUnit`.
Merge pull request #160 from dragos/issue/fix-slow-runas-menu

Made the Launchable Property tester use the presentation compiler.
Reviewers comments: added `override` and better documentation.

Also removed `batchSourceFile` from `InteractiveCompilationUnit`.
Merge pull request #167 from dragos/issue/java-parameter-names-completion

Insert Java parameter names in method completions.
Merge pull request #164 from dragos/improvements/small-refactorings-for-worksheet

Refactorings in compilation units
Merge pull request #169 from dragos/improvements/refactorings-for-worksheet-2

Improvements/refactorings for worksheet 2
add of testcase+fix for lazy vals in `find references`
Merge pull request #170 from sschaef/issue/find-ref-for-lazy-vals

added a testcase for lazy vals for `find references`
Fix crash in `TaskScanner` when encountering `NoPosition`.
Merge remote-tracking branch 'upstream/master'