Add run masking and URL reading to LumiList
Add list constuction mode and a way to find duplicates during construction
Fix a subtle bug do to re-used objects
Merge pull request #4064 from ericvaandering/72x_improve_lumilist

Improve LumiList
Merge remote branch 'origin/CMSSW_7_2_X' into CMSSW_7_0_X