PROOF and file I/O performance monitoring framework. The TVirtualPerfStats
abstract class allows adding monitoring events in base classes (TFile and
TNetfile). The performance monitoring info allows detailed study of PROOF
performance (which files accessed by which slaves, latency, read/write times,
packet size, etc.). The result is send back to the client in the form of a
memory based TTree.

Remove TProofStats.h and TProofStats.cxx, .d, .o from proof/inc and src.


git-svn-id: http://root.cern.ch/svn/root/trunk@9182 27541ba8-7e3a-0410-8455-c3a389f83636