network preflet: Make InterfaceListItem dumber

* Allows us to use InterfaceListItem for non-physical
interface things (like a VPN connection)

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: added BNetworkSettingsListener.

* Same as the configuration listener, just for SettingsUpdated().
* This is now broadcasted to all list items, too.

Network: fixed top item creation, sort entries.

* Need a way to access the NetworkWindow object from a static
method in order to sort all entries correctly, though.

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.

BNetworkSettingsAddOn: added missing destructor.

Network: integrated former hardware view from add-on.

* The interfaces logic is within the main application, so is the
new interface view.
* Disabling/renegotiating does not work yet.
* Reveals a bug in some interface code; when you click on an ethernet
device first, there is no place for the wireless menu. When you then
press on a wireless device, it crashes in BMenuField code.
In the other direction, there is then an empty space.
* Fixed list item width reporting.

Network: no need for public constants.

Network: moved add-on headers to the correct position.

* Ie. they've moved to headers/os/add-ons/network_settings now.

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: added BNetworkSettingsListener.

* Same as the configuration listener, just for SettingsUpdated().
* This is now broadcasted to all list items, too.

Network: fixed top item creation, sort entries.

* Need a way to access the NetworkWindow object from a static
method in order to sort all entries correctly, though.

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.

BNetworkSettingsAddOn: added missing destructor.

Network: integrated former hardware view from add-on.

* The interfaces logic is within the main application, so is the
new interface view.
* Disabling/renegotiating does not work yet.
* Reveals a bug in some interface code; when you click on an ethernet
device first, there is no place for the wireless menu. When you then
press on a wireless device, it crashes in BMenuField code.
In the other direction, there is then an empty space.
* Fixed list item width reporting.

Network: no need for public constants.

Network: moved add-on headers to the correct position.

* Ie. they've moved to headers/os/add-ons/network_settings now.