[ext] Remove use of cStringIO We create a StringIO never to read anything from it. Docutils seems to support setting the 'warning_stream' to False to ignore warnings. So let's just do that.

[view] Use io.BytesIO as stream for binary views

[undo/test] check that the entity was restored even though the fiche relation wasn't

Use a moved_entities table to record external entities moved to the system source Instead of using a negative eid in the entities table, move the record to a new table so we don't have an interval with a missing eid in entities. Related to #4846892

Add unique index on entities.extid

[undo/test] if we try to delete an entity referenced by an inline relation, we fail

[undo] when we can't undo an inlined relation change, point at None, not a broken eid This whole thing is "a bit" weird.

Ask sqlite to check foreign keys Related to #4846892

Add reference from etype table's eid column to the entities table Related to #4846892.

[server] change order of entities table modification vs entity creation/deletion In order to have a foreign key referencing the entities table, the insertion into entities must happen first, and the deletion must happen last. For the deletion case, this means we need to: 1. delete all relations (cascade) 2. delete the entities themselves 3. delete the corresponding lines from the entities table This means the _delete_info{,_multi} methods can't keep doing 1 and 3. Thankfully the "public" delete_info method appears to be unused, so drop it. Related to #4846892.