GL_NV_point_sprite
http://oss.sgi.com/projects/ogl-sample/registry/NV/point_sprite.txt
	GL_POINT_SPRITE_NV 0x8861
	GL_COORD_REPLACE_NV 0x8862
	GL_POINT_SPRITE_R_MODE_NV 0x8863
	void glPointParameteriNV (GLenum pname, GLint param)
	void glPointParameterivNV (GLenum pname, const GLint* params)