This cuts down on the memory requirements for skins by 25%, and
simplifies the shader a bit more, too. While at it, I made alias skins
nominally compatible with bsp textures: layer 0 is color, 1 is emissive,
and 2 is the color map (emissive was on 3).
It now takes a context pointer (opaque data) that holds the buffers it
uses for the temporary strings. If the context pointer is null, a static
context is used (making those uses of va NOT thread-safe). Most calls to
va use the static context, but all such calls have been formatted
consistently so they are easy to find when it comes time to do a full
audit.
This makes tex_t more generally useable and probably more portable. The
goal was to be able to use tex_t with data that is in a separate chunk
of memory.
They take a pointer to a free-list used for hashlinks so the hashlink
pools can be per-thread. However, hash tables that are not updated are
always thread-safe, so this affects only updates. progs_t has been set
up such that it is easy for multiple progs within one thread can share
hashlinks.
