Do we need to perform a gain matching for the FCAL simulation?

[igjaegle]

Note this issue is linked to issues #125 & #126.

In principle to match data and simu, the simulation should be calibrated in the same way than in the data i.e. a gain matching should be done for pi0 momentum corresponding to the most probable momentum observed in data
@sdobbs @rjones30 @andrsmit @somovalex @markdalton