Adding keyboard shortcut support everywhere.
This allows keyboard shortcuts to be used in the preference window.
Adding “Command-Q” termination support.
Adding “Command-W” support.
Adding missing “removeObserver:” call.
Cleanup.
Bringing all windows to front upon opening the menu.
Fixing preferences window reappearing if it was closed.
Merge pull request #9 from JanX2/UI-improvements

UI improvements