Added Dminor 120

Hey Everyone!

I have just added Dminor at 120BPM;  There are 19 melodies, and 8 chord progressions.

I also found a better workflow for this, so expect more frequent updates! In addition, I've also discovered there were errors in Cminor 120's exports, so I have elected to remove those for now until I have fixed them. I know it's a bit of one step forward one step back, but I've ensured that the loop pieces now loop perfectly.

Last thing; I'm considering adding MIDI files as well, for those who want more versatility out of this pack.