several improvements: protocol adjustments, diagnostic output, ACK handling, and shared configuration

[kaestnja]

Hello Oddvar,

I created this fork mainly for use in my lab, but over time I made several improvements: protocol adjustments, diagnostic output, ACK handling, and shared configuration. Since these might be useful for others as well, I would like to offer them back to the original project.

The license file was updated only to add my own copyright line ("Copyright (c) 2025, Jan Kästner") while keeping the original BSD 3-Clause terms unchanged.

If you consider these changes useful, I would be glad to contribute them upstream. Otherwise, I will continue maintaining my fork.