CppHighlighter: highlight all functions/methods.

- Highlight all function/methods (not just virtual methods).
- Highlight as a function even if number of arguments does not match. In
  that case, add a diagnostic message to indicate there are too many/too
  few arguments.
- Fix highlighting of parameters in function declarations.
  These used to be handled indiferently, and they could be mistaken for
  type or field references.
- Properly highlight template method calls.

Change-Id: I6ab463996dda47554839f482da47f561f76663a7
Reviewed-by: Erik Verbruggen <erik.verbruggen@nokia.com>