Remember the source from the database in the internal list source (stale data causes inconsistency otherwise)

Fixes #175

Assign the checked change listener before setting the state of the switch (restarts the VPN otherwise)

Implements #161

Implements #139

Implements #121

Implements #124

Implements #118

Implements #120

Implements #119

Deleting the rules async throws an exception when the source is delete before the rules referencing it

Implements #91