Simplify the code for allocating storage for intermediate results. Use fewer
temps in some cases.
Also, use new asm vec4_move intrinsic instead of regular assigments in various
constructors. For example:
float f;
vec3 v;
v.xyz = f;
is not legal GLSL, so do this instead:
__asm vec4_move v.xyz, f; // note: f will auto-expand into f.xxxx
Plus, fix assorted bugs in structure comparison.
