fly's eye part.

from SHMS shower counter. Make THcShowerArray a friend class to
THcShower in order to have access to the debug flags.

  Enable by defining HITPIC in THcShowerArray.h

  GetData accepts a pedestal range and an integration range.
  Samples in the integration range are added after subtracting the
  average of the pedestal range from each sample.
  Method also provided to return dynamic pedestal

  Added as an optional sub detector THcShowerArray to the THcShower class
  Get hit data with GetData method instead of hit member variables
    so as to be compatible with FADC compatible hit list