addcontainer didnt properly neutralized the filename leading to double names (sometimes) in the list of catalogs
scan status is now stored else setworkingcatalog will lead to too many rescans. rescans can be forced by the scan() method which always will scan
items were never filled if a catalog was recreated (after first create) from a resource. The content of the database was ok though so we refill from there
added a method to retrieve if a catalog is already known (and thus scanned) to prevent too many scans and changed the interface of removeitems to be consistent with the rest of the 'item' interfaces
thE Hash method didnot neutralize the names so duplicates could exist
added message when scan starts
isReadonly --> const
added methods for reporting which format(s) is used and a better readonly status method(s)