send is working for Elektron MDUW firmware 1.63

There are a lot of trashed commits because I am using this as a way to get better at c, and made many changes that I later decided were totally pointless. However, I have successfully been able to send samples to the machinedrum now! I know you said you don't have one anymore, so I don't know how interested you are in this pull request, but I thought I would send it nonetheless and also thank you for having some code that I could use as a starting point.