Network: made the revert button (somewhat) work.

* DNS add-on does not yet support it, the rest does.
* However, there seems to be some problems with the net_server when
changing interfaces -- not just with revert.

Network: added interface list item.

* Added BNetworkInterfaceListItem that can be used by interface protocol
add-ons to represent their functionality in the list view.
* It will automatically update itself on changes, and will show the
specified label, and address, if any, as well as indicate whether or
not the family has been disabled (which doesn't work perfectly yet,
as IFF_AUTO_CONFIGURED is on the interface level).
* Therefore, the interface list item will no longer show the address,
but the type of the device instead.
* Introduced the BNetworkConfigurationListener interface that is used
to broadcast network updates to.

Network: broadcast updates, remove apply button.

* Network now monitors all network, and network settings changes, and
will notify all add-ons about those changes.
* Removed the global apply button. Instead, the static IP configuration
now got that button. All other changes will be instant.

Network: added global settings.

* NetworkWindow now manages a single BNetworkSettings object
that is shared with all add-ons.

Added IPv4Interface add-on for Network preferences.

* Took over most code from the former InterfacesAddOn, and
moved it to where it should be.
* However, it doesn't work yet at all.

Network: made the revert button (somewhat) work.

* DNS add-on does not yet support it, the rest does.
* However, there seems to be some problems with the net_server when
changing interfaces -- not just with revert.

Network: added interface list item.

* Added BNetworkInterfaceListItem that can be used by interface protocol
add-ons to represent their functionality in the list view.
* It will automatically update itself on changes, and will show the
specified label, and address, if any, as well as indicate whether or
not the family has been disabled (which doesn't work perfectly yet,
as IFF_AUTO_CONFIGURED is on the interface level).
* Therefore, the interface list item will no longer show the address,
but the type of the device instead.
* Introduced the BNetworkConfigurationListener interface that is used
to broadcast network updates to.

Network: broadcast updates, remove apply button.

* Network now monitors all network, and network settings changes, and
will notify all add-ons about those changes.
* Removed the global apply button. Instead, the static IP configuration
now got that button. All other changes will be instant.

Network: added global settings.

* NetworkWindow now manages a single BNetworkSettings object
that is shared with all add-ons.

Added IPv4Interface add-on for Network preferences.

* Took over most code from the former InterfacesAddOn, and
moved it to where it should be.
* However, it doesn't work yet at all.