GL_EXT_texture_perturb_normal
http://www.opengl.org/registry/specs/gl/EXT/texture_perturb_normal.txt
GL_EXT_texture_perturb_normal
	GL_PERTURB_EXT 0x85AE
	GL_TEXTURE_NORMAL_EXT 0x85AF
	void glTextureNormalEXT (GLenum mode)