niflib: Add helper properties to shaders and fix type in versions.

include/nif_versions.h

include/obj/BSShaderNoLightingProperty.h

include/obj/BSShaderPPLightingProperty.h

include/obj/BSShaderProperty.h

include/obj/BSShaderTextureSet.h

include/obj/Lighting30ShaderProperty.h

include/obj/SkyShaderProperty.h

include/obj/TallGrassShaderProperty.h

include/obj/TileShaderProperty.h

src/obj/BSShaderNoLightingProperty.cpp

src/obj/BSShaderPPLightingProperty.cpp

src/obj/BSShaderProperty.cpp

src/obj/BSShaderTextureSet.cpp

src/obj/Lighting30ShaderProperty.cpp

src/obj/SkyShaderProperty.cpp

src/obj/TallGrassShaderProperty.cpp

src/obj/TileShaderProperty.cpp