Enabled the memory test in the new build

The test is run using 'memory-test' profile on org.scala-ide.sdt.core.tests
The full command line to run the test from org.scala-ide.sdt.build:
mvn --projects ../org.scala-ide.sdt.aspects,../org.scala-ide.sdt.core,../org.scala-ide.sdt.core.tests -P scala-2.10.x,memory-test clean integration-test
Added the Scala reflection library to the class path container.
Merge branch 'master' of github.com:scala-ide/scala-ide
Merge pull request #116 from skyluc/issue/memory-test-1001067

Enabled the memory test in the new build
Create fatal errors when a refactoring's initial check yields an error.

Until now, we created normal errors, which were shown in a wizard page,
and because they were non-fatal, the refactoring still tried to execute,
resulting in exceptions in the log file. Now we use fatal errors, which
immediately abort a refactoring and show the error message in a window.

Fixes scala-refactoring #76
No need to call setIsStructureKnown, as it is already done by the caller

In ``ScalaCompilationUnit#buildStructure``, there is no need to call
``setIsStructureKnown`` on the current compilation unit, as it's the
caller's responsability to do so.
``ScalaSelectionEngine`` uses now a ``ScalaCompilationUnit`` (instead of a
``ICompilationUnit``)

Both ``ScalaSelectionEngine`` constructor and the ``select`` method started
with casting the passed compilation unit to ``ScalaCompilationUnit``.  Beside
not being type safe, this unsafe cast is not needed, since clients of
``ScalaSelectionEngine`` can already pass a ``ScalaCompilationUnit``.
Refactoring in test plugin

Removed ``ScalaUnit`` type alias and replaced usage of ``ScalaUnit`` with ``ScalaSourceFile``.
prototyped testing framework
Need a good commit message
Find Method references should not return the declaration of the (re-)searched
method

When looking for references of method `xxx`, the method itself should not be
reported as a match. Indeed, find references is about finding usages of `xxx`,
not the declaration (and that is why a find declaration action exist).
No more "operation unavailable" popup on find references action

When Find References was performed on a val/var declaration, a popup dialog
used to be shown saying:

> The operation is unavailable on the current selection. Please select a valid
> Java element name.

The issue is in the compiler symbol found for the val/var declaration.
Apparently, the symbol's name can contain a trailing space (why??), which
caused the equality test between the editor's current selection and the
symbol's name to always fail.

The trivial fix is to trim the symbol's name.

A test was also created to prove the issue is now corrected.

Test #1000773
Tested find references for both class' constructor and class's type

Created tests to check that:

* class' constructor references are correctly reported.
* class' type references are correctly reported (also for type bounds).

Fix #1000063
I'm not sure this commit is actually meaningful
Tested find references for companion object members.
stashed: all tests pass
Added FindReferenceTests to regression suite
Better implementation of ``ScalaProject.sourceFolders``
big refactoring of find-references tests. Still need to clean up
minor change