Light improvements; some bugfixes

build/config_sys.cfg

build/engine/shaders/gdefines.h

build/engine/shaders/gi/gi_cubes.gs

build/engine/shaders/gi/gi_cubes.ps

build/engine/shaders/gi/gi_cubes.vs

build/engine/shaders/gi/gi_inject.gs

build/engine/shaders/gi/gi_inject.ps

build/engine/shaders/gi/gi_inject.vs

build/engine/shaders/gi/gi_inject_cube.vs

build/engine/shaders/gi/gi_propagation.cs

build/engine/shaders/lighting/lighting_blend.ps

build/engine/shaders/lighting/lighting_bound.vs

build/engine/shaders/lighting/lighting_com.ps

build/engine/shaders/lighting/lighting_gi.ps

build/engine/shaders/lpv.h

build/engine/shaders/mtrl.h

build/engine/shaders/mtrlgeom/mtrlgeom_base.ps

build/engine/shaders/mtrlgeom/mtrlgeom_mr.ps

build/engine/shaders/ppgensm/ppgensm_direct.ps

build/engine/shaders/ppgensm/ppgensm_point.ps