Improved Shader Remaps

[Daggolin]

The vanilla shader remaps don't handle lightmaps properly, leading to various issues:

• remapping a texture/shader to itself causes all instances to use the lightmap of the first instance, resulting in incorrect spots ("cow" look); this prevents the server from undoing some shader remaps
• remapping a texture/shader to a texture/shader that wasn't loaded causes the new shader to use the internal lightmapNone, making the new shader either completly dark or fullbright

In most situations these issues are undesired, but maps have utilized these effects to light up and darken areas by remapping shaders. For that reason the default behavior of the shader remaps should not be altered.

This branch introduces a new function R_RemapShaderAdvanced which support additional arguments to specify the desired mode of shader remapping (preserve, fullbright, none, vertex, 2d) and indirectly exposes it to servers via configstring 1399.

Screenshots to compare:

• Fullbright / Vanilla:
• Preserve:

[UncannyFish]

This pull request breaks code that expects the trap_R_RegisterShaderNoMip to return 0.

https://github.com/mvdevs/mvsdk/blob/f37abd190b4edd1490e9cee5853dcde9170b566b/code/cgame/cg_info.c#L116-L119

	levelshot = trap_R_RegisterShaderNoMip( va( "levelshots/%s", s ) );
	if ( !levelshot ) {
		levelshot = trap_R_RegisterShaderNoMip( "menu/art/unknownmap" );
	}

https://github.com/mvdevs/mvsdk/blob/f37abd190b4edd1490e9cee5853dcde9170b566b/code/cgame/cg_players.c#L521-L522
https://github.com/mvdevs/mvsdk/blob/f37abd190b4edd1490e9cee5853dcde9170b566b/code/cgame/cg_draw.c#L1763-L1766

	// Model icon for drawing the portrait on screen
	ci->modelIcon = trap_R_RegisterShaderNoMip ( va ( "models/players/%s/icon_%s", modelName, skinName ) );
	
	// ...
	
	if ( ci->modelIcon )
	{
		CG_DrawPic( cgs.screenWidth - size - 5, y, size, size, ci->modelIcon );
	}

Loading map without levelshot

Before this pull request:

After this pull request:

Loading model without icon

Before this pull request:

After this pull request: