Adds handling of non-ASCII characters.

Unicode characters no longer cause the script to terminate.

I added a try-except around the block which searches for tracks. Previously, the script would prematurely terminate when it ran into a non-ASCII character (Thanks, Michael Bublé), resulting in no tracks being added. Now the user will be informed of tracks which could not be ASCII-formatted if they wish to fix said tracks and re-run the script on them.