Set up foreign keys when editing event types.

BUG: Columns cannot be deleted if they are foreign keys, because
the actual field datatype is not passed to MSC.EditEventType
when fields are deleted from an event type.
Needs changes to html or javascript or whatever to
pass a proper FieldDataModel instead of a dummy one.
Tried to fix, but couldn't figure it out.
Merge branch 'master-dev' of https://github.com/foxhide/PKSU-Gruppearbejde into master-dev