Set content type to be text/html.

So we can do more advanced formatting later.
Added pre tag around agenda.

This is particularly so the remind agenda shows up properly (in all its ASCII
glory).
Include agenda in pre tag with calendar.

Combined the header and footer into a single "body" variable.  The pre tag now
includes both of these blocks of text.  The content of the script, however, is
not being included now, since it can not be easily eascaped (since the email
is in HTML).  It could be escaped with some simple string replacement, but
that should probably be best done in a Perl script or something.
Added font style to pre tag in email body.

The default monospaced font is very ugly.  Added inline CSS to the pre tag
that sets the font.  Much better!
Added second (backup) font.