* Get{Interface|Network|Service}() methods are now const.
* Added variants of Interface(), and Service() that are const.
* Added new BNetworkServiceSettings::IsRunning() convenience method that
reflects the status quo rather than the settings.
* Added (still incomplete) helper classes for the settings messages.
* The net_server now uses these classes for its interfaces, and services.
* Renamed service_address to service_connection, as that better matches
what it is used for.
* As experimental API class BNetworkSettings.
* Added add/remove methods for interfaces, and services, too.
* Moved the conversion of the wireless networks into the settings class,
too, so that it only gives out converted ones (but accepts both
variants).
