Bug 914: Newt OSX: Reset NSApp's presentationOptions @ windowClose0() / Assume having focus in fullscreen-mode

- Reset NSApp's presentationOptions @ windowClose0()

  Commit 69c334448cfe8af553fd97689137ecf8f996b378 started using the [NSApp setPresentationOptions: opts]
  but missed to reset to defaults @ windowClose0();

- Assume having focus in fullscreen-mode
  NewtMacWindow::windowDidBecomeKey()' is not always called in fullscreen-mode!

Note: OSX Fullscreen from a browser still shows the browser title-bar
until mouse-click. Don't know how to avoid this. Minor issue..