don't use R__GenerateInitInstance macro. Put back old code + add on same

line the R__UseDummy macro. Code was failing with classes with more than
one template argument. Reported by Bill Tanenbaum.


git-svn-id: http://root.cern.ch/svn/root/trunk@5187 27541ba8-7e3a-0410-8455-c3a389f83636