Navigation bar tweaks

- Toggle on/off (CyanogenMod already did but only for hw keys devices).
  Fusion allows all devices to do that for those using PIE apps.
- Nav bar dimensions (height and width)
- don't disable hw keys when navbar enabled, let do this manually.
- make working with modified hw keys code.

See also FWB 28e305c4093c341d06aaa7b6d99086e5d53b01f4

Signed-off-by: Dragon <dragon7780@hotmail.nl>