Updated scan queue/scheduler design

I finally finished putting the contents of a Friday afternoon brainstorm session together on the new scan queue. Some of the features will include scan priorities, better reoccuring scans, and pausing scans. Details can be found here: http://bitwarehouse.com/bloq/index.php?type=archiv&post=200403#prispevek13 . Brent's already started work on the new vscd and we're also working on writing database interface functions in Perl.