GL_EXT_texture_compression_dxt1
http://www.opengl.org/registry/specs/EXT/texture_compression_dxt1.txt
GL_EXT_texture_compression_dxt1
	GL_COMPRESSED_RGB_S3TC_DXT1_EXT 0x83F0
	GL_COMPRESSED_RGBA_S3TC_DXT1_EXT 0x83F1
