Recognize more versions of the iTunes library file

[cbfiddle]

I have made some changes that allow the parser to recognize newer formats of the iTunes library file. I have tested these changes by examining the tracks that it finds in several of the files in Previous iTunes Libraries. These changes break several of the existing tests. As these tests were created many years ago, they may not be valid. I have accomplished my goals and do not plan to do any further work on this project. I am submitting my changes in case anyone finds them useful.