Cleanup compiled Python bytecode before startup.
Don't crash on field validation errors. See #1234.
BSSID is allowed to be null.
Ensure that onLoad event handlers get called.

Previously, this caused the Leaflet-based widgets to not
be reloaded when a field change causes the form to be
rendered again.
Don't duplicate protocol field choices.
Handle builder configuration errors.
Removed preconfigured rules.
Fixed ValueError being thrown in field clean.
Fixed incorrect instance overwriting.