doxygen support for comments

[David Nolden]

The simplest way to achieve this would be doing something similar to
the way macros are dealed in C++.

It's done by simply analyzing the code under the cursor on demand, and
detecting "special language objects". See
CppLanguageSupport::specialLanguageObjectRange,
specialLanguageObjectJumpCursor and
specialLanguageObjectNavigationWidget.

It would be relatively easy to implement:
1. Scan the word under the cursor
2. Scan the word at the left side of it
3. Is it a special doxygen tag? If yes, do something fancy.

Greetings, David