AutoDJ Improvements and Refactoring

by Tom Mast for Mixxx

This project will work on the AutoDJ part of Mixxx and provide these improvements: 1.) Add the ability for the DJ to specify Fade In/Fade Out points that hold over after the session ends 2.) Provide a simplistic way of adjusting the time it takes Mixxx to complete the automatic crossfade between tracks 3.) Add the option for certain decks to be specified as the AutoDJ decks 4.) Refactor the existing AutoDJ code, adding a SongTransition class to handle song synchronization