GL_EXT_blend_equation_separate
http://oss.sgi.com/projects/ogl-sample/registry/EXT/blend_equation_separate.txt
	GL_BLEND_EQUATION_RGB_EXT 0x8009
	GL_BLEND_EQUATION_ALPHA_EXT 0x883D
	void glBlendEquationSeparateEXT (GLenum modeRGB, GLenum modeAlpha)