* largely re-organized the playback routines
* replay the same episode no longer goes through player prepare process
* fixed not seeking past the recorded duration of an episode
* duration if less than played position is amended to played position
* long-press on Rewind also sets slider position to 0
* added experimental feature of playing 2 episodes at same time
* code to move clips in migration since 10.12 is removed
* upped SDK and target to 37 (Android 17)
