Add testEfficiencyTable.cc

Added code to test the EfficiencyTable code and make sure it returns the
right efficiency. It does doe so now, after making a tweak to the PU
counting to account for the fact that the text file adds one to the
maxPU column to allow Kevin's script to work.
Update WeightDistribution.cc

Removed a unused struct.

Fixed help text to properly reflect the renaming.

Fixed a comment left over from the old version.