GPU renderer backend change

[kpreid]

GPU renderer backend change

[kpreid]

Commit 3c3f64f added wgpu web glue (accessed by ?renderer=wgpu), but all block colors are missing; I have not yet investigated the cause.

[kpreid]

Commit 47c2a5a added a workaround for the info text drop shadow.

[kpreid]

Commit e4c0571 fixes wgpu rendering on web; it was a thing where WebGL uniform layout pads even individual integers out to vec4 size, so my struct declaration was incompatible. I wonder whether wgpu should be doing something about that (at least linting) since it's a silent compatibility failure.

[kpreid]

Commit ff2f120 implements debug chunk boxes.

Commit 12d383c implements volumetric transparency.

Note: Chunk box line colors are also off, which suggests that the oddity in the light ray debug lines is something general in the lines vertices or lines shader.

[kpreid]

I've decided that the wgpu renderer is good enough to make default, in 325f356. Further fixes/improvements will be considered individually.