Rewrite skin handling for dynamic remapping

Previously you would need a skin file for every way you wanted to remap a model.
Now you can setup/change skins using code. This allowing surfaces to toggle between
two shaders based on code or have multiple shaders for different damage levels
(without being limited to entire model or a ton of skin files).

Move skin file loading to cgame.
Merge player skins into one skin (will be useful for single model players later).

New system calls;

trap_R_RegisterShaderEx -- exposes ability to register shaders with 'lightmapIndex' other than LIGHTMAP_2D.
trap_R_AllocSkinSurface -- create reference for surface name/shader.
trap_R_AddSkinToFrame -- add skin (list of skin surfaces) for referencing in refEntity customSkin, must call each frame.
Fix compiling dedicated server
#6069: Remove md4 model support.
Merge remote-tracking branch 'ioquake3/master'

Conflicts:
	code/renderergl1/tr_animation.c
	code/renderergl1/tr_local.h
	code/renderergl1/tr_model.c
	code/renderergl2/tr_animation.c
	code/renderergl2/tr_local.h
	code/renderergl2/tr_model.c
OpenGL2: Remove redundant GLS_* enum.

Thanks Xycaleth for pointing out.
Remove R_AddAnimSurfaces and R_MakeAnimModel prototypes
Add "nodraw" shader for disabling surfaces in skins

Move hack for not drawing surfaces listed with missing shader in skin to cgame.
Fix glsl DEFORM_BULGE calculation
Merge pull request #21 from cmf028/master

Fix glsl DEFORM_BULGE calculation
Merge remote-tracking branch 'ioquake3/master'
Start using VM API version

Not maintaining backward compatibility yet, but lets start to
keep track of API break so we can error if unsupported.

Add API name.
Allow server to create cvars on client again

If connecting to server with different fs_game, might not of registered the cvars in cgame yet
(so create it so cgame can get the value).

Don't mark server created cvars as read-only (they'll be stuck that way), but still don't let user change them.
Change order of refusing to set cvar so we tell user cvar is server created before read-only etc.
Fix loading game VM

Have game VM error when missing vmMain command.
Give CGame more control of refEntity_t lighting

Replace RF_MINLIGHT with float ambientLight[3].
Add RF_CONST_AMBIENT to only use ambientLight from entity.
Add RF_NO_DIRECTED_LIGHT to disable directed light.
Restore minimum light add in cgame

Not added to misc_gamemodel or sprites.
Fix white flash levelshot bug in OpenGL1

If you tried to draw the last loaded image, gl texture 0 (which is appearently white)
was used because renderer thought the image was already bound.

Why OpenGL1 renderer binds texture 0, I have no idea. It's been removed from OpenGL2.
r_noborder changes require a restart
Add latch to r_centerWindow and r_allowResize
Support spatialized raw streams in base sound, e.g. for VoIP
Merge remote-tracking branch 'ioquake3/master'

Conflicts:
	code/renderergl1/tr_init.c
	code/renderergl2/tr_init.c
	code/sdl/sdl_glimp.c