v0.19.6

Oriel 0.19.6

Added

• Android apps can keep running with no window in front, for work that
  isn't audio (a file server for the user's other devices, a sync engine):
  .android.keep_running = "why" declares a foreground service of type
  specialUse (the text is the subtype Google Play reviews), and
  oriel.android.setKeepRunning(on, title, text, actions) starts and stops
  it with an ongoing notification and its buttons. With
  .window.hide_on_close, swiping the app away from Recents leaves it
  running. oriel.android.batteryUnrestricted() and
  oriel.android.openAppSettings() help the user exempt it from battery
  optimization. The microphone service (setForegroundService) is
  unchanged.