Thread Support in ROOT (3)

Recently started an overhaul of the thread classes
- In a backward compatible way gPad has been made a function (using a macro and a CINT trick). No special version of the ROOT libraries needed anymore.
- Added some new classes like: TRWLock, TLockGuard and TThreadPool
- Usage of global locks around event processor
Major problem remaining: usage of g++ iostreams causes a deadlock (still not fixed in 2.95)

Recently started an overhaul of the thread classes