fixed some dynamic lighting bugs related to glowing self

fixed some dynamic lighting bugs related to glowing self
rmeshstate_t now has alphascale
now clears stencil from shadows differently (draws shadow volume over again to clear)
R_LightModel now does GL_Color or GL_UseColorArray depending on whether the model has any shading
model->DrawBaseLighting function is gone, now just a few special cases in the normal Draw function
removed R_NotCulledBox
added PVS_CullBox, R_CullSphere, and PVS_CullSphere
visiblevolume flag is gone from shadow rendering code (visible volumes are now automatic depending on what stage the shadow system is in)
R_DrawShadowVolumes is gone (now just a special option to R_ShadowVolumeLighting)
cubemap textures now upload correctly
doubled the bumpyness of surfaces to make bumpmapping noticable (still less than tenebrae)
fixed crash when loading external map textures
now supports _luma as an alternate name for _glow map textures (tenebrae compatibility)
can now override _bump, _gloss, and _glow/_luma textures that were generated from the map
bumpmapping works on the map now (that was a stupid typo...)
now uses alpha buffering for multi-pass lighting effects
r_shadows 3 now works on Geforce2 (2tex no3D 3 pass per layer) and Radeon (2tex 3D 2 pass per layer - Radeon has 3 texture units but the lighting code is most efficient with 2 units, and 3D textures use up 2 texture units on Radeon... lame...)
gloss isn't working yet
r_shadows 3 mode supports up to 64x overbright lighting now (by rendering light multiple times)
fixed palettes (this fixes oddities like seeing sky behind fullbrights)

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@2531 d7cf8633-e32d-0410-b094-e92efae38249