Add support for more key events (#64)

In some cases tcell sends Key{Ctrl,Alt}{Up,Down} events instead of
Key{Up,Down} event that have the corresponding modifier mask set.
(these key combinations are used for switching rooms)

ui/view-main.go

@@ -195,6 +195,10 @@ func (view *MainView) KeyEventHandler(roomView *RoomView, key *tcell.EventKey) *
 		default:
 			return key
 		}
+	} else if k == tcell.KeyAltDown || k == tcell.KeyCtrlDown {
+		view.SwitchRoom(view.roomList.Next())
+	} else if k == tcell.KeyAltUp || k == tcell.KeyCtrlUp {
+		view.SwitchRoom(view.roomList.Previous())
 	} else if k == tcell.KeyPgUp || k == tcell.KeyPgDn || k == tcell.KeyUp || k == tcell.KeyDown || k == tcell.KeyEnd || k == tcell.KeyHome {
 		msgView := roomView.MessageView()