Finished initial separation into two executables:
   - SortTrees.C: Replaces Main.C.  Contains main() for initial sort of trees, compiles to SortTrees.
   - SortHistos.C: Contains main() for sorting histograms.  Compiles to SortHistos.
Created Util.C and Utils.h which contains all the helper functions which were in Main.C.

Both SortTrees and SortHistos now compile and run properly.