merged databases into its own database (and also keep them up to date).
Furthermore added code to properly destroy merged databases and their
providers in desctrutor.
scanning local directories and filling its ResourcesDB.
The ResourcesDB is responsible for writing local catalogue files. It
automatically loads back the appropriate catalogue file (depending on
the provider that operates on the ResourcesDB object) at initialization.
Will be useful for WebResourcesProvider as well to cache metadata of
online resources.
All you have to do now is to create an according ResourcesProvider which
will automatically setup a ResourcesDB that can be operated on by the
ResourcesTreeModel.
and hash-map) - avoids local copies of objects as well as accidently
overwritten ResourcesDB::Item's in hash-map, which resulted in
inconsistencies in tree and finally crashes in several situations, e.g
removal of previously existing objects (closes#2584125)
