new HP-IL software implementation in C++20

[MeindertKuipers]

Great work Eric, especially doing this from scratch. I have implemented the HP82160A interface for the HP41 in my PICO/HP41 interface, and used the existing V41 sources (Christoph Giesselink), which in turn are based in JF Garniers EMU41. I was really happy to have something existing which I could adapt. But a validated reference source would be good to have, as it may cover corner cases.