Visual parity

current status (maybe we can write a wiki page so we can contribute):

feature	todo	wip	done	ref	parity action
color grading				0	???
r_glsl_deluxemapping				0	???
glow			x	1	load _glow/_luma implicitly
normal			x	1,2	load _norm implicitly
gloss			x	1	load _gloss implicitly
bump (height)		x		3	load _bump implicitly, implement normal from height
dpoffsetmapping			x	1,4,5	implement
zip symlink			x	6	implement
sRGB lightmap	x			7	implement
dpwater		x		8	implement
dpreflectcube			x	2	implement
dpglossintensitymod	x			11	implement
dpglossexponentmod	x			11	implement
dp shader keywords		x		9	implement
xon shader keywords		x		9	implement
shader extra maps		x		1,10	implement
image extra maps		x		1,10	implement
jpg alpha sidecar	x				load _alpha implicitly
warp zones	x			12	implement

ref	status	proof
0	???	isn't there already such things in Dæmon?
1	done	ParseShader: load extra maps the DarkPlaces way if r_dpMaterial enabled
2	done	refactor and fix normalmap, parallax, reflectionmap, glowmap, GL/DX normal switch
3	wip	renderer: compute normalmap from heightmap when missing normalmap, aka bumpmap
4	done	R_UploadImage: detect heightmap in normalmap alphachanel
5	done	parallax mapping bugs
6	done	Archive-level symlink support
7	todo	there is no such thing in Dæmon yet
8	todo	renderer: revive liquid shader (currently disabled because it is broken)
9	wip	do not abort shader on “unknown general shader parameter” warning
10	wip	make dpMaterials collapsed shader from the start, including non-shader images
11	todo	Dæmon seems to already support those features but with other keyword names
12	todo	This is not only visual