proposal: Specify the use of `lang` for transliterated names

see: http://tools.ietf.org/html/bcp47#section-2.2.3 (esp. all the stuff around "script")
see: http://en.wikipedia.org/wiki/Romanization
see: http://en.wikipedia.org/wiki/ISO_15924
see: http://www.unicode.org/iso15924/iso15924-codes.html
Additional specification of a catch-all name form transliteration case

When the original language is not known, what do you put for the
transliterated name form script lang?  This represents my best guess.