dsync: Rewritten syncing for mailbox renames. A few things didn't go as I originally intended in the algorithm, but it appears to give consistent results now. :) But the algorithm should probably be looked at more closely at some point.

Array API changed: ARRAY_DEFINE(name, type) -> ARRAY(type) name Easy way to update your existing code: perl -i -pe 's:ARRAY_DEFINE\(([^,]+), *([^)]+)\);:ARRAY($2) $1;:' **/*.[ch]

Hash table API is now (mostly) type safe.

Initial version of dsync rewrite. * doveadm backup not implemented at all yet * syncing mailbox renames is somewhat broken (at least renaming \noselect mailboxes) * saving/restoring "state" is implemented by dsync brain, but not by doveadm. this should be easy to do, just need to figure out how the replication code wants it.