Internal update

• ExoPlayer version up to 2.4.0, using full module set.
• Add PlayerManager#savePlaybackState, PlayerManager#restorePlaybackState, PlayerManager#getPlaybackState, PlayerManager#getPlaybackStates.
• PlaybackState implement Parcelable to help saving/restoring states in Activity/Fragment recreation.
• Add ExoPlayerView and ViewHolders built around it. ExoPlayerView use official SimpleExoPlayerView with some improvement. ViewHolders use this also need to provide a MediaSource. Util class ExoPlayerHelper is added to help building MediaSource easily.
• Demo apps is updated with removing the use of deprecated classes.
• Facebook sample is updated with fine-crafted Full screen playback.
• Many other small updates.

Bug Fixes

• Fix #186: Single item list now plays video correctly, sample added to demo app.
• Fix #193: NPE when unregistering RecyclerView.
• Fix #190: Updating ExoPlayer also fix this issue of NoClassDefFoundError of AdaptiveVideoTrackSelection.
• Fix #183: Now loop playback will work correctly. Also it is not recommended when using with LoopMediaSource.
• Fix #174: A trick to work around this rare state.
• Fix #167.

Maybe more issues are fixed along with this release.

Deprecated

• Toro#attach(Activity) and Toro#detach(Activity) are now deprecated. Using registering directly (View context must be an Activity).
• ExoVideoView and those ViewHolder built around it are deprecated. Use ExoPlayerView and the ViewHolders built around it.
• Deprecate PlayerManager#saveVideoState, PlayerManager#restoreVideoState, PlayerManager#getSavedState. These methods will be removed in next big release.

Known issues

• ToroViewPagerHelper is not working well. Solution for ViewPager is under investigation.
• Facebook sample may contain some memory leak, just ignore it for now.