AltME groups: search

For instance, some of the words are definitely handled as special-cases, 
rather than as normal word characters. Different follow sets in those 
cases too.

The escape decoding gets done too early. The decoding should not 
be done after until the URI structure has been parsed. If you do 
the escape decoding too early, characters that are escaped so that 
they won't be treated as syntax characters (like /) are treated as 
syntax characters erroneously. This is a bad problem for schemes 
like HTTP or FTP that can use usernames and passwords, because the 
passwords in particular either get corrupted or have inappropriately 
restricted character sets. IDN encoding should be put off until the 
last minute too, once we add support for Unicode to the url handlers 
of HTTP, plus any others that should support that standard.