GL_EXT_blend_equation_separate
http://www.opengl.org/registry/specs/EXT/blend_equation_separate.txt
	GL_BLEND_EQUATION_RGB_EXT 0x8009
	GL_BLEND_EQUATION_ALPHA_EXT 0x883D
	void glBlendEquationSeparateEXT (GLenum modeRGB, GLenum modeAlpha)
