WIP: Add Brem support in v2 Event Model
Add Brem support in v2 (SOA) Event Model. Here basic Brem-Corrected accessors are added that would easily translate to functors with names like "BREMCORRPT(...)". An alternative of adding an optional boolean argument to the pre-existing accessors would (I think?) make it easier to add functors like "BREMCORR(PT(...))". Aiming to fix LHCb#107. Dependent on LHCb!3046 (closed).