Drop the old catalog compat code
We introduced the catalog in Ideascube 0.9.0.
Then we split the local cache/storage in Ideascube 0.11.0, adding some code to migrate the boxes to the new format.
This compatibility code is ugly and unwieldy, and it's starting to be a pain to maintain it. (see !803 (merged) for example)
We need to remove it at some point, the sooner the better.
We have two options:
- wait until we have no more boxes between 0.9.0 and 0.11.0 (i.e either older versions, or newer)
- drop it without waiting, and upgrades will need a manual migration.