Currently, next-error always outputs a message "next locus from
<buffer>". In the vast majority of cases, <buffer> does not change from
one message to the next, so this message is just annoying.

The attached patch changes it so the message is only output when the
locus changes.

It also gets rid of the "first/current/previous" options; what matters
is where the _next_ error will come from.

Comments?

-- 
-- Stephe