This fixes the problem of using nil for two different compound types
within the one expression. The problem is all compound types have the
same low-level type (ev_invalid) and this caused the two different nils
to have the same type when taken back up to expression level.
Only as scalars, I still need to think about what to do for vectors and
quaternions due to param size issues. Also, doubles are not yet
guaranteed to be correctly aligned.
After messing with SIMD stuff for a little, I think I now understand why
the industry went with xyzw instead of the mathematical wxyz. Anyway, this
will make for less pain in the future (assuming I got everything).
Rather than prefixing free_ to the supplied name, suffix _freelist to the
supplied name. The biggest advantage of this is it allows the free-list to
be a structure member. It also cleans up the name-space a little.
Also move the ALLOC/FREE macros from qfcc.h to QF/alloc.h (needed to for
set.c).
Both modules are more generally useful than just for qfcc (eg, set
builtins for ruamoko).
With the intoduction of the statement type enum came a prefix clash. As
"st" makes sense for "statement type", I decided that "storage class"
should be "sc". Although there haven't been any problems as of yet, I
decided it would be a good idea to clean up the clash now. It also helps
avoid confusion (I was a bit surprised after working with st_assign etc to
be reminded of st_extern etc).
qfcc isn't meant to be long running, so I'm not super worried about memory
usage, but definitely lost memory blocks when compiling just a single
function seems a tad sloppy.
