Conkeror has the bindings [[ and ]] for follow-relationship-previous and follow-relationship-next,
two very convenient commands.  However, we could wring more utility out of them by factoring out the
"relationship finding" parts of the code into two new browser object classes, bound on the keys [ and ].

Such refactoring would mean a gain of ability to do things like `] c' for "copy relationship-next", etc.

The main problem blocking such a feature is that we would lose the nice double-key bindings of [[ and ]].
However, vim has this kind of feature, where you hit a key representing a command, then hit the same key
again, and because the context has changed, it knows that the second keypress refers to a text object. 
(Conkeror's semantics are the other way around: object class first, then command.)  For example, vim's
`d d' and `y y' bindings.  We should consider copying this kind of design in conkeror, but also carefully
consider whether it will introduce any limitations to the further development of the browser objects
system.

It is possible to have ] and [ mean follow once a browser object prefix has been given.  One question is
whether you ever would actually want to use something like "] c".  To me it seems somewhat unlikely,
because you can't really be sure what you'll be linking to.

I seem to recall wishing I could do "] c" one or two times in the past, probably just as a quick way to
find out what conkeror's relationship code finds on the current page.  The focus command would be useful
in this context for the same reason ("] ;").

implemented this a while ago