Missing patch from Ben Skeggs:

Missing patch from Ben Skeggs:

Lots of changes, and fixes for some badness on my behalf.

1. Disposable data used during fp compile is now per-context,
   rather than per-program to save memory.

2. Track usage of INPUT/TEMP registers from Mesa program, free
   them when no longer required so the hw temps can be re-used.

3. Changed LAST_NODE to OUTPUT_COLOR (see r300_reg.h)

4. Implemented remaining ARB_f_p instructions, with the exception
   of the trig/LIT opcodes.

5. Treat ZERO/ONE swizzles the same way as other native swizzles.

6. emit_arith changes, basically a complete re-write.  Should
   produce cleaner instructions, but no real functional changes.
   internal reg -> hw reg routines shared with emit_tex.  A bit
   messy still.