This patch eliminates TVirtualProof, TVirtualProofMgr and TVirtualProofDesc.
The first is integrated in TProof, the second in TProofMgr and the third
becomes TProofDesc defined in TProofMgr.h.


git-svn-id: http://root.cern.ch/svn/root/trunk@16969 27541ba8-7e3a-0410-8455-c3a389f83636