Add a new parameter Xaero_tdc_offset to make sure valid tdc
  hits from a reference time corrected tdc are positive.
  Accept first first positve tdc hit after applying offset.
  Move array filling in CoarseProcess into Decode

  THcRawHodoHit gives reference time corrected TDC values
  THcScintillator plane adds a per plane offset to the raw tdc value
  First positive TDC value after adding offset is used

  Fix bad Addmodule argument (refchan)
  Print warning if expected reference time is missing
     (Probably means event is bad)

  (Assignment probably not actually done with these objects,
  so we might want to remove these methods.)

  May want to use a hit class that doesn't inherit from THcHodoscope
  as the Cerenkov is not using Neg tubes or TDCs.

  Separate methods for ref time subtracted and raw hits

Update THcHodoScope and THcScintillatorPlane to get focal plane time for each plane

used to determine focal plane time for each hodoscope plane.
Add code to THcScintillatorPlane:DefineVariables to write out
focal plane time, number of paddles hit that passed minimal TDc cut
and number of paddle hit that were used in determining the focal plane time.
Add calls to THcScintillatorPlane.h to Set and Get the focal plane time
and number of paddle hits used to determine focal plane time for each hodoscope plane.

  Nint of an Int gave a compiler error in newer gcc
  Commented out local variables that are not used

  If the podd docs are built using the ROOT tagfile, then when the hcana
  docs are built using the podd tag file, doxygen crashes.  This commit
  adds building of the podd docs to the hcana doc building Makefile.  The
  podd docs are built without using the ROOT tagfile, so a sed hack is used
  to modify podd's Doxyfile.

  Use ROOT's xml layout file
    Customize for hcana, with Hall C logo
  Use tag files from podd and ROOT
  Use groups, starting with a Detector group

  docs/Makefile now builds doxygen docs in docs/html
  If you want documentation to be build elsewhere, define
  DOXYGEN_OUTPUT_DIRECTORY and run doxygen by hand

Doyxgen setup