Implement subnet match rules.
Idempotency deletion.

Sometimes the diff won't contain enough information to determine whether or
not a particular device to delete is actually on the target host or not.
Fix doc formatting.
Filter tunnels and interfaces with local info.

Hosts should only create tunnels and interfaces for which they possess the
relative local end and subnets, respectively.
Read nameserver and web port from configuration.
Better comments for network configuration.