GL_ATI_separate_stencil
http://www.ati.com/developer/sdk/RadeonSDK/Html/Info/ATI_separate_stencil.txt
	GL_STENCIL_BACK_FUNC_ATI 0x8800
	GL_STENCIL_BACK_FAIL_ATI 0x8801
	GL_STENCIL_BACK_PASS_DEPTH_FAIL_ATI 0x8802
	GL_STENCIL_BACK_PASS_DEPTH_PASS_ATI 0x8803
	void glStencilOpSeparateATI (GLenum face, GLenum sfail, GLenum dpfail, GLenum dppass)
	void glStencilFuncSeparateATI (GLenum frontfunc, GLenum backfunc, GLint ref, GLuint mask)