KT: active window getter for XWrapper.
KT: keep track of active window, highlight it.
Core: changed ActionButton highlighting style.
Core: relative highlight bar widths.
KT: moved WinStateFlags to separate file.
KT: added per-window modification signals to XWrapper.
KT: ignore PropertyDelete notifies.
KT: Subscribe() for events subscription.
KT: support updating window info.
KT: added allowed actions flags.
KT: getter/notifier for window actions.
KT: use allowed actions.
KT: reflect minimized/active property in quark.