Source file extension changes (cc to cpp)

[joevenzon]

GL_MAX_DRAW_BUFFERS is not used at the moment, so you could really just ignore that line and set the variable to zero. Or, if supporting 10.3 isn't necessary, then leaving as it is would ensure that if it does get used down the line you won't have to change anything later.

I don't think the coplanar_tri_tri() function is used anymore by VDrift. You can comment it out and everything will probably be fine. I'll go through and gut utility.cpp pretty soon. Using ODE 0.8 is fine. Note that some have reported crashes when ODE 0.8 is compiled with gimpact instead of OPCODE, although I think it's due to a bug so I'm not sure if it'd crash on OS X too or not.