Moving DataMaker classes from graphics to rec, to be able to reuse
them in the QA phase.
AliMUONVTrackerDataMaker.h
Added a ProcessEvent method. The existing NextEvent method should now
do only the advance-to-next-event stuff, the actual processing should
be done in ProcessEvent. This allows the data makers to be used with
rawreader they can "touch" (i.e. use NextEvent/Rewind), and with
rawreader they can not.