Due to the plethora of historical baggage from different eras getting
confusing, I decided to simplify and unify the struct organization and
naming scheme.
Structs that got renamed:
1. fbodst -> ra_fbo (and moved to gpu/context.h)
2. fbotex -> removed (redundant after 2af2fa7a)
3. fbosurface -> surface
4. img_tex -> image
In addition to these structs being renamed, all of the names have been
made consistent. The new scheme is as follows:
struct image img;
struct ra_tex *tex;
struct ra_fbo fbo;
This also affects derived names, e.g. indirect_fbo -> indirect_tex.
Notably also, finish_pass_fbo -> finish_pass_tex and finish_pass_direct
-> finish_pass_fbo.
The new equivalent of fbotex_change() is called ra_tex_resize().
This commit (should) contain no logic changes, just renaming a bunch of
crap.