This takes care of the global variables to a point (there is still the
global struct shared between the non-vulkan renderers), but it also
takes care of glsl's points-only rendering.
After yesterday's crazy marathon editing all the particles files, and
starting to do another big change to them today, I realized that I
really do need to merge them down. All the actual spawning is now in the
client library (though particle insertion will need to be moved). GLSL
particle rendering is semi-broken in that it now does only points (until
I come up with a way to select between points and quads (probably a
context object, which I need anyway for Vulkan)).
This gets the pipelines loaded (and unloaded on shutdown). Probably the
easy part :P. Still need to sort out the command buffers,
synchronization, and particle generation (and probably a bunch else
that's not coming to mind).
