implemented sorting music library alphabetically
added in comments
made the playbar only show part of the song title if it is too long to fit in the bar
removed the comparable logic from the model
moved the sorting into its own method and reordered the map along with the sorting
Merge pull request #67 from ejohnson44/order_music_library

Order music library
Merge pull request #69 from ejohnson44/playbar_UI

Playbar ui part 2