fixing compiler errors and testing validation in 7_2_X
adapt higgstautau config for 72X
minor tweak to higgstautau config for 70X
and finally adding miniaod config for 72X
updating comments in Example.cpp
bit of spring cleaning in the HiggsTauTau package
Updates for Phys14 studies

  * In Plotting.h PositionedLegend now supports creating a TLegend at
    the bottom of the canvas - in either the left (4), centre (5) or
    right (6) positions
  * Add functions to JsonTools that take care of merging json files
  * and/or json fragments together
CombineHarvester updates

 * Tidy-up documentation of CombineHarvester.h
 * CombineHarvester::AddSyst will now output some helpful information
   when verbosity is >= 1. This includes: a list of SystMap entries that
   were never used to build a Systematic, a list of Process entries that
   were encountered but didn't get a Systematic, and a list of Process
   entries that were encountered and did get a Systematic.
 * To facilitate the previous feature, some code added to Utilities to
   print the contents of any std::tuple
 * Added a function to determine the relative path between two files,
   which is now used in WriteDatacard to give the correct path to the
   ROOT File when the user puts it in a different folder.
 * Updated SMLegacyExample to build the datacard folder structure in the
   same way as the existing tools: e.g. `110/ 115/ 120/ 125/ common/`