Fix Doxygen handling of XMLWRAPP_* macros.
Fix Doxygen handling of XMLWRAPP_* macros.

The XMLWRAPP_DEPRECATED macro in particular wasn't parsed correctly by
Doxygen, resulting in ugly, confusing noise in the generated docs.

Also predefine XMLWRAPP_API to hide it from the docs.

vadz/xmlwrapp,vslavik/xmlwrapp,vadz/xmlwrapp,vslavik/xmlwrapp,vadz/xmlwrapp,vslavik/xmlwrapp