Added render to depth texture support with GL_EXT_framebuffer_object. Only render the shadow/depth texture when really needed, not every frame. Remove support for old SGIX shadow extensions.
Added render to depth texture support with GL_EXT_framebuffer_object.
Only render the shadow/depth texture when really needed, not every frame.
Remove support for old SGIX shadow extensions.

djreep81/glsl-optimizer,KTXSoftware/glsl2agal,zeux/glsl-optimizer,jbarczak/glsl-optimizer,zeux/glsl-optimizer,dellis1972/glsl-optimizer,mcanthony/glsl-optimizer,djreep81/glsl-optimizer,KTXSoftware/glsl2agal,metora/MesaGLSLCompiler,tokyovigilante/glsl-optimizer,bkaradzic/glsl-optimizer,adobe/glsl2agal,zz85/glsl-optimizer,tokyovigilante/glsl-optimizer,mapbox/glsl-optimizer,adobe/glsl2agal,dellis1972/glsl-optimizer,bkaradzic/glsl-optimizer,tokyovigilante/glsl-optimizer,benaadams/glsl-optimizer,mapbox/glsl-optimizer,djreep81/glsl-optimizer,KTXSoftware/glsl2agal,dellis1972/glsl-optimizer,mcanthony/glsl-optimizer,wolf96/glsl-optimizer,jbarczak/glsl-optimizer,zeux/glsl-optimizer,mcanthony/glsl-optimizer,adobe/glsl2agal,jbarczak/glsl-optimizer,zz85/glsl-optimizer,zeux/glsl-optimizer,wolf96/glsl-optimizer,dellis1972/glsl-optimizer,jbarczak/glsl-optimizer,bkaradzic/glsl-optimizer,zz85/glsl-optimizer,zz85/glsl-optimizer,metora/MesaGLSLCompiler,benaadams/glsl-optimizer,djreep81/glsl-optimizer,benaadams/glsl-optimizer,adobe/glsl2agal,zz85/glsl-optimizer,mcanthony/glsl-optimizer,jbarczak/glsl-optimizer,adobe/glsl2agal,mapbox/glsl-optimizer,tokyovigilante/glsl-optimizer,bkaradzic/glsl-optimizer,wolf96/glsl-optimizer,benaadams/glsl-optimizer,mcanthony/glsl-optimizer,wolf96/glsl-optimizer,KTXSoftware/glsl2agal,mapbox/glsl-optimizer,benaadams/glsl-optimizer,zz85/glsl-optimizer,wolf96/glsl-optimizer,KTXSoftware/glsl2agal,bkaradzic/glsl-optimizer,zeux/glsl-optimizer,benaadams/glsl-optimizer,djreep81/glsl-optimizer,dellis1972/glsl-optimizer,mapbox/glsl-optimizer,metora/MesaGLSLCompiler,tokyovigilante/glsl-optimizer