- Objective C/C++ was not enabled in highlighter.
- QMake project part for Objective C/C++ did not have ObjectiveC extension enabled.
- As languageFeatures.objCEnabled is a bitfield, it was actually always set to 0.
- Highlight ObjC class & protocol declarations.
- Highlight ObjC message passing.

Change-Id: I64d12c9509058d05f7adce94598cb7ce91727ac8
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>