JiffyDOS protocol implementation for VIC-20
Includes code and information from the following sources:
https://www.forum64.de/index.php?thread/35519-sjload-20-v07/
https://github.com/gummyworm/skippydos
https://www.c64-wiki.com/wiki/SJLOAD
https://sites.google.com/site/h2obsession/CBM/C128/JiffySoft128