The foreign keys have 'ON DELETE CASCADE' to simplify the removal
of networks etc. (controller code)
Some unique constraints are replaced with a multi column primary
key.
To update an existing database:
* install updated binaries
* stop service
* sqlite3 controller.db .dump | \
egrep '((^PRAGMA)|(^BEGIN)|(^INSERT)|(^COMMIT))' | \
grep -v 'schemaVersion' > data.sql
* mv controller.db controller.db.backup
* start service
* stop service
* sqlite3 controller.db < data.sql
* start service
