Merge pull request #5551 from bendavid/pythia8200pre2interface

Pythia8.200pre2 interface changes
properly initialize event attributes in pythia8 lhe interface
update key configuration snippets for pythia 8.2 and create organized fragments for common pythia8 settings
improve comment in config file
proper accounting for merging weights from CKKWL, UMEPS, UNLOPS
explicit DQMIO in datatier of GEN relvals
cleanup unused GEN fragment
backport compilation fix
Merge pull request #5749 from davidlange6/RecoAlgos_72x

backport compilation fix
Merge pull request #5727 from franzoni/GEN-relval-CMSSW_7_2_0_pre7

Gen relval cmssw 7 2 0 pre7
Merge pull request #5602 from bendavid/pythia8_200pre2_72x

Pythia 8.200pre2 (72x)
Merge remote branch 'origin/CMSSW_7_2_X' into CMSSW_7_0_X