make tau r21 updates flexible (ThinningUtils-00-00-17)

  * ThinTrackParticlesTool: make compatible with xAOD::TauJet_v2 and _v3 (r20 and r21)
  * tag ThinningUtils-00-00-17

2016-04-26 Justin Griffiths <griffith@cern.ch>
  * ThinTrackParticlesTool: make compatible with xAOD::TauJet_v3 (r21)
  * tag ThinningUtils-00-00-16

2015-10-14  Karsten Koeneke  <karsten.koeneke@cern.ch>

  * ThinTrackParticles: Add flag to only take the first n TrackParticles for each electron
  * tag ThinningUtils-00-00-15

2015-08-20 Will Buttinger <will@cern.ch>
  * src/ThinIParticlesTool : extended to allow taking a mask from the storegate instead of using an expression
  * Tagging ThinningUtils-00-00-14


Former-commit-id: 9a232faacd914f7a0c412b3d96ae3f0fd99cdeb7