GL_EXT_draw_buffers2
http://www.opengl.org/registry/specs/gl/EXT/draw_buffers2.txt
GL_EXT_draw_buffers2
	void glColorMaskIndexedEXT (GLuint buf, GLboolean r, GLboolean g, GLboolean b, GLboolean a)
	void glDisableIndexedEXT (GLenum target, GLuint index)
	void glEnableIndexedEXT (GLenum target, GLuint index)
	void glGetBooleanIndexedvEXT (GLenum value, GLuint index, GLboolean* data)
	void glGetIntegerIndexedvEXT (GLenum value, GLuint index, GLint* data)
	GLboolean glIsEnabledIndexedEXT (GLenum target, GLuint index)
