GL_EXT_packed_pixels
http://oss.sgi.com/projects/ogl-sample/registry/EXT/packed_pixels.txt
	GL_UNSIGNED_BYTE_3_3_2_EXT 0x8032
	GL_UNSIGNED_SHORT_4_4_4_4_EXT 0x8033
	GL_UNSIGNED_SHORT_5_5_5_1_EXT 0x8034
	GL_UNSIGNED_INT_8_8_8_8_EXT 0x8035
	GL_UNSIGNED_INT_10_10_10_2_EXT 0x8036