Share code with ResolveExpression.

Unmark the visited nodes when searching bindings in class or namespace scopes.

As a side-effect, we can finally complete things like connect(&a, SIGNAL(

Unfortunately, the MacroResolver does not scale and we get pretty bad performances when parsing big projects.

Introduced T_CPP_COMMENT and T_CPP_DOXY_COMMENT to handle C++-style comments and improved CPPEditor::isInComment to handle the newly introduced tokens.

As side effect,this change should fix the regression we introduced in the "automagically" quote/brace insertion.

In particular macros that are only checked for definition or are
expanded during the evaluation of an #if or #elif directive are now also
added to the list available through Document::macroUses().

The names of undefined macros that are interesting (because they're used
in an #ifdef or a defined(...)) are now available through
Document::undefinedMacroUses().

Reviewed-by: Roberto Raggi <roberto.raggi@nokia.com>