Large update. See extended description

1. First step chosen from the midi file is placed into a new array as
placing it in the 3D probability matrix did not make sense.
2. Fixed the markov chain runthrough which outputs a sequence of pitch
values <- need to now construct midi file with this.
3. Used standard library vectors,pair and sort functionality to choose
next state according to probability.

Things needing to be done: Sort out mess, clean up variable names,
produce midi file from analysed tracks