Saving an order of magnitude less information in closeditems_saved, and speeding up another order of magnitude the syncing of closeditems_saved by eliminating redundant syncs.

Things will get even better in following commits, but for now closeditems_saved shouldn't be hundreds of kbs big (or even 1-2 mb!) anymore, and it should be much faster now to load & save thecloseditems_saved config file.