Minor cleanup to light.
Merge branch 'dev' of https://github.com/c-f-h/vpinball into dev
Fixed frame time counters and made max reset periodically.
Flippers: fixed an issue with the normals; some cleanup.
VP9 compatibility: made pure black bumpers invisible.
Fixed rendering of decals on backdrop.
Fixed lights not working on the backdrop. Also some optimizations to texture coordinate computation.