Beginning of work to separate out code into two executables, one for tree sorts, one for histogram sorts. See https://github.com/carlu/GRSISpoon_Calibrations/issues/2

Started by separating code for storing configuration and reading commmand line options from Main.C and adding into Options.C.  It should now be able to be called from main() of either bit of code.
Renamed several files to more sensible names given new plans.
SortTrees.C - contains main() for sorts acting on fragment trees.  Previously Main.C.
SortTrees.h - all the main/global header stuff which is not in Options.h. Previously Main.h.
SortHistos.C - main() for sorts acting on histograms.  Previously CalibSpectra.C.

References to headers updated in all other files.
SortTrees.C, SortTrees exectutable now compiling and working.  There may be some teething trouble with plots etc but the histogram stuff has been stripped out and the tree stuff still works.
SortHistos.C does not yet compile, working on that next.
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.