shaders: Remove some ET only shaders.

[DolceTriade]

Remove sunShader and flareShader. They are only used in ET and not
actually used anywhere in the engine. They just spam us.

[slipher]

LGTM

[illwieckz]

For information if we want to reimplement them the missing images can be found in XreaL (old zip release, not repository).

[illwieckz]

Si I looked at the code and even the RB_DrawSun function is missing from our tree.

I sometime have the strong feeling OpenWolf was not forked from latest ET:XreaL…

The sun shader is a special shader to display a sun on the skybox like this (here in ET:Legacy, Oasis map):

Providing the needed assets and setting r_drawSun 1 in Dæmon does nothing (RB_DrawSun function is missing…).

If we want to implement this one day, the data is there (from XreaL_PreAlpha_20080704.7z):

https://dl.illwieckz.net/b/daemon/features/xreal-missing-shaders/engine-xreal_0.dpk

For some unknown reason the data is shipped in XreaL_PreAlpha_20080704.7z but there is no code for it, and the data is not shipped in ETXreaL-0.3.0-20111110 but there is code for it)…

[illwieckz]

@DolceTriade you may want to also delete the r_drawSun cvar, that was to enable/disable sunShader.