Appeal to ISO 639 RA in support of Elfdalian

[Shawn Steele]

> You don't want to know how long the process took just to get RFC 4646 and 4647, and later RFC 5646, through the IETF.

Unfortunately, standards work isn't always lightning fast.

I think that for Mats to be unblocked with his efforts, he should choose a private use tag for immediate use.  Then if this is all untangled in 6 or 12 months he can migrate to the "official" tag, whatever it may be.

-Shawn