[q2x] Refactorization

[Brian Hook]

I'm in the midst of a gnarly global update (s/byte/qbyte).  Bleh.

Anyway, opinions on whether to keep the software renderer or not?  I'm 
pretty torn about this.  On the one hand, running on low-end systems 
reliably would be kind of nice for any project.  On the other hand, 
being able to rip out all semblance of paletted support would be nice 
(unfortunately, PCX support would still have to remain because a lot 
of stock assets are still in PCX form).

The engineer in me really likes deleting code and minimizing 
maintenance.  The pragmatist in me, however, would really like to keep 
the ability to run on shitty machines.

I'm leaning towards ripping it out, because it should be easy enough 
to run reliably on even basic 3D acceleration from 1998.

BTW, the missing asset error messages were the result of a bug in 
physics fs which has been fixed.

Brian