De-QObject-ify the factories and registries

There is no reason for the registries and the factories the registries contain to be QObjects. The only thing it was used for was the parent-child relation so the factories would be deleted on shutdown.

The objects would thus both be in the hashmap and in the list of children of the registry, effectively clouding the ownership relation.

To make all registries in KOffice consistent in usage, the destructors of the registries now delete their contents, there is no parent-child relationship anymore.

It also saves memory and makes it clear where all these objects are destroyed