Steps to switch to IRIs:

* Extend character sets in `OFURI` to allow Unicode, but only allow Unicode private characters in the query.
  (`iprivate       = %xE000-F8FF / %xF0000-FFFFD / %x100000-10FFFD`)
* Add methods to escape only Unicode
* Use these methods in all HTTP classes
* Rename `OFURI` to `OFIRI`