Work on keyword completion.
Fix a bug.
Merge remote-tracking branch 'origin/hardcase_work' into DependentProperties

Conflicts:
	Nitra/Nitra.Runtime/Nitra.Runtime.nproj
Work on keyword completion.
Rename IDeclarableParseTree to IMappedParseTree.
Rename GetDeclaration method to GetAst.
Rename DeclarationUtils to AstUtils.