Added single kaon gun generation fragments

Renamed single pion gun generation fragments
Added MinBias gen fragment

Copied from: https://github.com/cms-sw/genproductions/blob/master/python/FourteenTeV/MinBias_TuneZ2star_14TeV_pythia6_cff.py
Added MinBias gen fragment used by Seb Viret

Adapted from: https://github.com/sviret/HL_LHC/blob/master/DataProduction/test/base/SLHC_MBIAS_BASE.py
Reference: CMS-PAS-GEN-14-001 <https://cds.cern.ch/record/1697700/>
Added TTbar gen fragment

Copied from: https://github.com/cms-sw/genproductions/blob/master/python/FourteenTeV/PYTHIA6_Tauola_TTbar_TuneZ2star_14TeV_cff.py
Added TTbarTTbar gen fragment used by Seb Viret

Adapted from: https://github.com/sviret/HL_LHC/blob/master/DataProduction/test/base/SLHC_PU_4T_BASE.py
Drop more xml files in XMLIdealGeometryESSource when using the tracker only
Drop more subdetectors when using the tracker only

Impose slightly tighter selection on TrackingParticles
Modified pileup mixing input source

Added private pileup mixing input source
Added TrackingParticle flags: signal, stable, primary
Don't use prunedGenParticles

It prunes away pions and kaons
Added drawer_patternbank.py

Minor edit in drawer_amsim.py
Merge pull request #21 from jiafulow/prepare-v024-2

Added generation fragments