Multiple render passes are needed for supporting shadow mapping, and
this is a huge step towards breaking the Vulkan render free of Quake,
and hopefully will lead the way for breaking the GL renderers free as
well.
First pixels! This was a nightmare of little issues that the validation
layers couldn't help with: incorrect input assembly, incorrect vertex
attribute specs. Though the layers did help with getting the queues
working. Still, lots of work to go but this is a major breakthrough as
I now have access to visual debugging for textures and the like.
Short wrappers for Draw functins are in vid_render_vulkan.c so the
vulkan context can be passed on to the actual functions. The 2D shaders
are set up similar to those in glsl, but with full 32-bit color (rgba)
support instead of paletted. However, the textures are not loaded yet,
nor is anything bound.
