Extract the TQClass declaration from the TQObject header.

The TQClass declaration is only needed in the dictionaries and
introduce a spurrious depedency of any TQObject on TClass.h
CVS ----------------------------------------------------------------------


git-svn-id: http://root.cern.ch/svn/root/trunk@14335 27541ba8-7e3a-0410-8455-c3a389f83636