* Resolving some issues with media playback.
* Changing ViewVideoFragment so that it fully handles autohiding the
media controller, allowing consistency between it and the toolbar
* Fixed an issue where the toolbar and description were not fading in
* Do not hide the toolbar/media player if the video is loading or paused
* Created "ExposedPlayPausedVideoView" to allow hooking play/pause
* Fix back button when viewing videos
* Back button did not work if video controls were visible.
* Tweak audio player
* Always show the controls when audio begins playing
* Do not auto-hide the controls if the player is playing audio
* Address PR comments
* Use overloaded constructor
* Remove m prefix
* Fix subtle media player issues
* Fix audio player incorrectly auto-hiding after hiding/showing toolbar
* Only subscribe touch listener once content is ready
- Prevents top toolbar visibility from getting out of phase with audio player visibility if hidden during load
* Fix media transitions, reduce code duplication between media fragments
* Remove redundant helper
* Fix occasional crash when swiping between mixed media
* Hide controls when swiping between media
* Migrate ImagePagerAdapter to kotlin
* Migrate ViewMediaFragment to kotlin
* Make images and videos share the same activity/pager
* Show descriptions above videos
* Cleanup
* Address code review feedback
* Migrate media fragments to constraint layout
Vivianne