[development] internationalised paths in URI (was subdomain rewriting)

[drupal]

Staying on the url() issue, I think we should consider implementing the
recommendations of:
http://www.ietf.org/rfc/rfc3987.txt

At least the path side. At the moment non-ascii characters are dropped
from paths, at least when using path alias.

IMO it should be done. This will help supporting with various
internationalised websites.

A decent overview can be found in
http://www.w3.org/International/articles/idn-and-iri/

Cheers,
Vlado