Rebuilding GLSL shaders that don't need a `vid_restart`

[illwieckz]

I would like to see a mechanism that can rebuild a GLSL shader without needing a vid_restart.

I assume this would be doable for GLSL shaders not requiring to load any new data.

Not candidates:

• r_normalMapping (requires shader parsing and image loading)
• r_drawSky (requires shader parsing and image loading)
• r_lightMode (requires bsp loading and image loading)

Candidates:

• r_toneMapping
• r_colorGrading (as far as I know the way colorGrade images are loaded may make it possible)