As of a recent nvidia driver update, it became necessary to enable the
feature. I guess older drivers (or vulkan validation layers?) were a bit
slack in their checking (or perhaps I didn't actually get those lighting
changes working at the time despite having committed them).
Id Software had pretty much nothing to do with the vulkan renderer (they
still get credit for code that's heavily based on the original quake
code, of course).
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.
It turned out I needed access to the physical device from a buffer
object, so rather than storing the vulkan logical device directly in
buffer (and other) objects, store the qfv logical device.
