Change over to using SensitiveDetector to store info on the ROOT file and
disable the use of SteppingAction.

- This required that analysis be passed onto SensitiveDetector
- Comment out most of the SteppingAction code
- Everything that is not an optical photon that deposits energy on a sensitive
  detector is included
- No cuts placed on optical photons (that is, no minimum or maximun energy cuts
  besides those that are specified by the GDML file's properties)
- Each individual physical volume stores info in the ROOT file