WeakCollection<T>: use Equals() in Remove() implementation. This is necessary to make the use as WeakCollection<EventHandler> work as expected.
Update to NRefactory version aa289c2.

aa289c2 Fix potential NullReferenceException in OperatorIsCanBeUsedIssue.
9db72dc Fix icsharpcode/NRefactory#377 - NullReferenceException in NullAnalysisVisitor
db2c7b6 Add IAstVisitor.VisitNullNode().
95141c8 Fix ICompilation.Import(ISymbol) for namespaces in extern alias.
c05dbd0 Handle errors if the XML file changes between the XmlDocumentationProvider ctor call and the GetDocumentation call.
e763376 Fixed bug in FunctionNeverReturnsIssue.
168b76f Formatting options change: blank lines are now >minimum< blank lines. TODO: Add options for maximum blank lines to preserve.
fde2a06 Fixed bug in 'XmlDocIssue'.
1403af7 Added 'CS1105ExtensionMethodMustBeDeclaredStaticAction'.
acca096 Merge pull request icsharpcode/NRefactory#381 from mono-soc-2013/MateY-IndentEngine
505c974 Issue with preprocessor directives.
4730eca Added some indenting unit tests.
412b324 Fixed possible parser bug.
989abdd Fixed completion bug.
3582f57 Fixed bug in StaticEventSubscriptionIssue
bbe2d12 Merge pull request icsharpcode/NRefactory#380 from Therzok/patch-2
43b42c5 Merge pull request icsharpcode/NRefactory#379 from Therzok/patch-1
02278d8 Fix typo in documentation
f08bcdb Add StaticEventSubscription static check test
084d2de StaticEventSubscriptionIssue - Check if static
b7ab0b1 Implemented StaticEventSubscriptionIssue
aa291c5 Fixed construct fixer tests.
dd6db96 Fixed unit test bug.
6899688 Fixed constructfixer tests on windows.
3d42715 Improved display location for 'RedundantBoolCompareIssue'.
c1b8ab5 Removed IndentStateFactory. (Creating the classes direcly is a magnitude faster)
e7b490e Optimized IsNewLine method.
d95fdc2 Added some optimizations to the indent engine.
313235e Speed up indentation engine
540af30 Fixed indentation bug.
7db77a4 Added some more construct fix cases. Unfortunately the parser error recovery isn't good enough for implementing that feature.
bd6d6f1 Added c# ConstructFixer.