Auto-collapse disconnected networks

Steps

1. On a Quassel core, disconnect from a network while leaving another network connected
2. Connect via Quassel desktop
3. Connect via Quasseldroid

Expected

Both collapse the disconnected network, as it's not expected to be used.

Actual

Quassel desktop collapses the disconnected network by default, but Quasseldroid leaves it expanded.

Additional

There was a period of time when Quassel desktop did not do this, either. That was a regression from stable releases and it's been fixed.

Quassel Web also behaves like the desktop client.