This extension allows adding labels to vulkan objects and insert string
labels into command buffers. This is visible in tools like RenderDoc and
helps with debugging a lot.
When running with -vkdebug:
- mark all texture VkImages and VkImageViews with corresponding names
- label brush model draw calls accordingly
1. Improve performance by coalescing multiple surfaces/draw calls with
the same textures (within a single brush model).
2. Add lightmaps. We don't support lightstyles yet, though, so they seem
a bit wrong at times. Also gamma handling is not great.
Oh well.
