EMI: Read vertex color values from sprite files.

This makes the coals in wed more transparent, matching the original game better.
EMI: Draw model faces with alpha textures also to the depth buffer. Fixes #874
EMI: When a chore is stopped, remove it immediately from the list of playing chores.

If the chore is not stopped immediately, its components will still be drawn in the next frame, which is wrong. This caused flicker when entering the closeup at Stan's house.
EMI: Sprite drawing fixes for OpenGLS renderer.
EMI: Read depth write and alpha test flags from sprite files.