Network settings overhaul [WIP]

Goals
1. Merge NetworkManager and the panel [Done by in backport]
2. Fix wireless networks list, button to connect to a network not a single click, context menu to remove or edit, known networks on top separated from others, hide unknown? Make New Hidden networks an item on the list instead of a button.
3. Improve icons and other UI elements such as placement of buttons [In progress]
4. In proxy, when none is selected, the fields for the proxy settings still show up [Fixed by backport]
5. Show IP address for wireless possibly others [Fixed by backport]
6. [??] Make useable in XFCE/MATE/Elementary by allowing it as a standalone??

Any others?