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: I6e61c9ee47763db95c62314f9cc1c4d398df38b3
Reviewed-by: Leandro Melo <leandro.melo@nokia.com>

src/plugins/texteditor/texteditorconstants.cpp

@@ -61,6 +61,7 @@ const char *nameForStyle(TextStyle style)
     case C_FIELD:               return "Field";
     case C_STATIC:              return "Static";
     case C_VIRTUAL_METHOD:      return "VirtualMethod";
+    case C_FUNCTION:            return "Function";
     case C_KEYWORD:             return "Keyword";
     case C_OPERATOR:            return "Operator";
     case C_PREPROCESSOR:        return "Preprocessor";