Add debugging colors to textures.
Enable alpha blending for all compositing operations.
Loop: Add helpers to form the main loop.
Add a bunch more stuff.
Materials: Draw a couple other things.

So, uh, yeah. Definitely not seeing that texture on the left.
Fix up stuff.

Found the culprit!
Util: Make checkerboard actually appear checkered.
Permit some IO-only stuff to be done once-only on startup.
hlint.
Particles: Fix overlapping name.