add the capability to read MMC messages to the DLL

[micahstubbs]

from Pasi, via email

Thank you for doing the 64 bit conversion of midi4ahk! I am using the library for a AHK script and have stumbled on a problem. I am using the beatstep controller from Arturia and they have hardcoded stop and play on the buttons. They are supposed to be user configurable but they're not. I am using the play button for a toggle because it lights up but the stop button interferes with this. Would it be possible to add the capability to read MMC messages to the DLL? My plan is to keep track of the toggle state in software since it's not working on the hardware level. This is the first time I am doing anything that even resembles programming so I am quite a bit out of my depth.

[micahstubbs]

https://en.wikipedia.org/wiki/MIDI_Machine_Control#:~:text=MIDI%20Machine%20Control%2C%20or%20MMC,Stop%2C%20Pause%2C%20and%20Record.

[micahstubbs]

I don't think I'll be able to do this quickly/soon, but I'm happy to review code and help test this if someone in the community wants to send a PR