improved weight names, JetMatching Hook, GravFlat Hook (Pythia8_i-00-12-02)

  * Updated weight storage so that names instead of ids are used in the HepMC record
  * tagging Pythia8_i-00-12-02

2015-09-08  James Monk  <jmonk@cern.ch>
  * Added JetMatchingMadGraphHook.cxx for FxFx matching

2015-08-02  James Monk <jmonk@cern.ch>
  *  Updated version of GravFlat UserHook from Jan Stark for 13 TeV running

2015-06-16  James Monk <jmonk@cern.ch>
  *  reinstate use of map syntax so that weight names are stored in HepMC

2015-06-08  James Monk	<jmonk@cern.ch>
  *  Merging branch for Pythia 8.205 with multiple LHE3 weights onto trunk

2015-05-18  James Monk  <jmonk@cern.ch>
	* Check order of LHE3 weights on each event is the same
	  * write MetaData in finalize giving the weight descriptions

2015-03-18  James Monk	<jmonk@cern.ch>
...
(Long ChangeLog diff - truncated)