Updates to tnl_dd_dmatmp.h

Updates to tnl_dd_dmatmp.h
	- Allocate vertices explicitly, rather than trying to talk
	  about dma buffers.
	- Clean up the various Flush() operations.
	- Don't allow fallbacks any longer.  Provide a support function
	  to detect them ahead o ftime
Updates to tnl_dd_vbtmp.h
	- Get rid of power-of-two vertex strides.  Pack all vertices tightly.
	- Get texunit 2,3 emit working coorrectly.
Other stuff:
	- Get rid of lingering Ubyte color support.
	- Fix a few compiler warnings.