Draft: In Run5, run Digitization of FT detector alone , forwarding all packed MCHits from previous Gauss step.

FYI : @mwhitehe , @lgrillo , @clangenb

Work taken from @leuecker for 'holing' FT. Current code do NOT depend on FTVolumeID. could do, but FTVolumeID != FTChannelID , it can be renamed probably {Det}SensDetIDDecoder.h

• Patches done to 'forward' MCHits in TV/UP/MP should be better coded in Configuration.py application. TO be seen if other sub-detectors should forward things to .digi file or not.
• FT digitisation currently not using the FTVolumeID classes (MCHit->sensDetID() decoder) and relying on m_ftDet finding info based on x-y-z of MCHits. (safe approach for U2-FT?)

TODO :

• Move TrackInfo_U2 creator currently at Boole step-- not needed, we need to create it at Reco level until we run tracking over MCHits on other trackers?
• However the Cluster2MCParticle and Cluster2MCHit linkers should be produced for FT in Boole
• Update Configuration.py to know about Run5. Fast-forward pSim hits in subdetectors ( which subdetectors beside TV/UP/MT ? RICH/Calo/Muon/Torch(?)/MagnetStation )
• NB: MCHits from MCParticle in Tracks defines the AccDet detector. HasDet flags for trackers has to come at Moore as TV/UP/MP MChits-post-smearing that are used for reconstruction.
• If a digitisation is done for Trackers using MCHits , the HasDet mechanism and Linker tables And TrackInfo must be stored in Boole, and Rec just consume it.