Merge branch 'maddin/textures-phillipk2x-cleanup' into 'master'

Merge branch 'maddin/textures-phillipk2x-cleanup' into 'master'

Maddin/textures phillipk2x cleanup

This cleans up the phillipk2x shaders and adds some features:
* Overall better formatting of the shader file.
* Shaders that have an alpha channel, like grates, now work properly.
* Decals are now decals and not opaque textures.
* The glow of all light and computer textures has been adjusted to show their respective colour instead of pure white.

See merge request !46