URL naming
----------

/$LISTNAME/?before=$GIT_COMMIT                  -> HTML only
/$LISTNAME/index.atom.xml                       -> Atom feed
/$LISTNAME/all.atom.xml                         -> Atom feed, includes replies
/$LISTNAME/m/$MESSAGE_ID.html                   -> HTML content (short quotes)
/$LISTNAME/m/$MESSAGE_ID.txt                    -> raw original
/$LISTNAME/m/$MESSAGE_ID                        -> 301 to .html version
/$LISTNAME/f/$MESSAGE_ID.html                   -> HTML content (full quotes)
/$LISTNAME/f/$MESSAGE_ID                        -> 301 to .html version
/$LISTNAME/f/$MESSAGE_ID.txt                    -> 301 to m/$MESSAGE_ID.txt
/$LISTNAME/t/$MESSAGE_ID.html                   -> HTML content of thread
/$LISTNAME/t/$MESSAGE_ID.mbox                   -> mbox content of thread

We use file name suffixes on all of these (except /) so URLs may easily
cached/memoized using a static file server.