href2

Given a base href and a relative href, return the absolute href that
matches the relative one.  The process is guided by rfc1808.  To
receive a copy send email to GradeBot with:

   Subject: rfc1808

Note that no course is specified.  rfc1808 is about 900 lines long.
Section 2.4 explains how to parse the url into its six parts, which
are <scheme://netloc/path;param?query#fragment>.  Section 4 explains
how combine the base and embedded (relative) urls into a single
absolute url.