[plt-scheme] Recent changes to DrScheme (and related) in SVN

For details on using the intermediate releases, see

  http://svn.plt-scheme.org/

This is a summary of the recent changes to DrScheme in the
SVN archive. You may have some of these changes already;
typically each change is committed as it happens and these
emails are only sent when the list gets long enough.

  . Help Desk's font size is now independently configurable
    (from Drscheme's font size).

  . Help Desk no longer asks about non-http urls; it always
    just ships them off to the OS to handle.

  . Various url struct changes to fix bugs related to
    mailto: url handling and handling of multiple params in
    a path segment.

    . the scheme and host are now always lowercased by
      string->url

    . the library no longer adds an empty path to the end of
      urls like "http://www.drscheme.org", meaning that the
      url-path can sometimes now be an empty list (the
      contract always allowed this, but it didn't happen
      before).

    . added path-absolute? field to url struct, following
      rfc 3986's nomenclature -- when #t, it means the path
      portion of the url began with a slash and when #f it
      means that it didn't.

    . more care is taken when quoting path portions of the url
      and when turning urls into strings

    . path segments are now always path/param structs and
      the param part of a path/param struct is now a list of
      strings

    . add 'up and 'same as possible path segments (in the
      path field of a path/param struct), in addition to
      strings (as before).

Robby