- Simplify some code that was mainly duplicating accessAttribute().

 - Improve accessAttribute() with ideas from the removed copies.
   -- Yes, I changed the method signature twice in three patches...

- Replace QList with QVector in internalContextsForClass(), make type
ptr const.

- Remove unused return in getDocumentationFileContext().
- Remove unused -typedef QPair<Declaration*, int> p; in
declarationbuilder.cpp.