combine diffs and full sync with --interval

It would be helpful if I could run ldappc-ng in a manner like

bin/gsh.sh -ldappcng -bulkSync -interval 180 86400

so that there would continue to be 'diffs' done with a cycle of every 180 seconds, but once every 86400 seconds (or 1 day) instead of a diff a 'full' sync would be done. By 'full' I mean the type of synchronization that happens when I first start up ldappc-ng. During the 'full' sync the diffs would be skipped.

This operation mode would help put to rest doubts that some have about the generic process of 'sync fully once then do diffs forever'. I have no evidence that ldappc-ng gets out of sync over time doing just diffs, but I have managers that are certain is must happen as t -> /infinity.