#add FClass and FClasses added to encapsulate (and ultimately replace) UClass and FClassTree.
#add StringUtils contains a bunch of string-related functions which were in FHeaderParser for no real reason.
#change Replaced FClassTree with UHT and fixed up all the code which was affected.
#codereview robert.manuszewski
[CL 2045258 by Steve Robb in Main branch]
