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 notify settings updated method.

* And call it from the DNS client -- this is the only add-on that does
not trigger a configuration or settings update, so we have to notify
the changes manually.

Network/DNS settings: apply button, improved layout.

* The buttons now all end up with the same width.
* Put the grid into a BBox.
* The new "apply" button will actually apply the changes.

Network: DNSSettingsView style cleanup.

Network: beginnings of the DNS settings.

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 notify settings updated method.

* And call it from the DNS client -- this is the only add-on that does
not trigger a configuration or settings update, so we have to notify
the changes manually.

Network/DNS settings: apply button, improved layout.

* The buttons now all end up with the same width.
* Put the grid into a BBox.
* The new "apply" button will actually apply the changes.

Network: DNSSettingsView style cleanup.

Network: beginnings of the DNS settings.