Issue: Editing Area Makes it Disappear

When editing an existing area, whether in the Admin Panel or via the editor, the area goes missing after saving. Sniffing the database reveals that the prefix ID on the route has changed.

This is due to the area's default prefix ID using the same field name as the revision's prefix ID that is used to generate the path for a wiki page. Further, the default prefix ID field is redundant now that the area has a separate field for a list of valid prefix IDs.

Fixed by removing the prefixid field from the database and removing the remaining references from the source code.