release build: v04.09.00

major feature enhancements

* new 'Settings' menu item
  - offers 3 options to configure how video URLs will be watched:
    * internal video player w/ Chromecast sender
      - default option
      - same behavior as previous app versions
        * uses ExoPlayer to watch video url
          - all HTTP requests include the referer url
        * when the video url is cast to Chromecast
          - the referer url is ignored,
            because Chromecast receiver apps aren't allowed
            to change this HTTP request header
    * external video player
      - starts an implicit Intent
        * allows any app with a matching Intent filter to take over
        * only includes the video url (data) and mime-type (type)
    * ExoAirPlayer sender
      - works with the receiver app:
          github.com/warren-bank/Android-ExoPlayer-AirPlay-Receiver
      - loads the URL in a WebView:
          'http://webcast-reloaded.surge.sh/airplay_sender.html' +
          `#/watch/${base64_video}/referer/${base64_referer}`
      - this page prepopulates the form fields from URL hash:
        * video url
        * referer url
      - this page prepopulates the form fields from previous use:
        * host
        * port
        * https
      - this page provides a basic UI to control any receiver app
        that is reachable through the network

caveats

* when using the 'ExoAirPlayer sender'
  - the page that loads in a WebView uses modern javascript
    * this is incompatible with very old web browsers,
      such as the native WebView in Android prior to 5.0
    * this issue will be addressed in a future release