[KBSwitch] Listeners initialization.
[KBSwitch] Group names.
[KBSwitch] Instantiate KBCtl in desktop mode.
[KBSwitch] KBCtl is singleton & X11 event handler now.
[KBSwitch] Handle interesting X11 events.
[KBSwitch] Per-window layout switching policies.
[Util] Don't check for LC window in ShouldShow().