Added specular_reflect to Photon.py and implemented it.  Also added its use to Simulation.py.  Left an unimplemented non_specular_reflect in Photon.py
Added TODO to Photon.py
Changed functions Simulation.py uses.  Added an elaboration on how to implement Circle.py.  Implemented specular_reflect and added empty non_specular_reflect and is_trapped to Photon.py.  Did something to Material.py apparently.