[plt-scheme] URI query parsing (or not)

Another difference between v208 and v299 that isn't in notes/HISTORY
or MzScheme_300.txt: `uri-query' (from "url.ss" in the "net"
collection) now returns an alist instead of a string or #f.
(Should I collect these into one post and/or bug report instead of
reporting each one as I find it as I'm upgrading my servlets?)

By the way, according to RFC 2396, the query component can be any
arbitrary string; in particular, it doesn't have to include an equals
sign.  It would be nice if there were a way to get the raw string,
because `alist->form-urlencoded' (from "uri-codec.ss") can be different:

> (alist->form-urlencoded (url-query (string->url "http://example.com/?foobar")))
"foobar="

--dougo at place.org