HP41 TULIP4041 update

[MeindertKuipers]

Just uploaded all sources again to https://github.com/mjakuipers/TULIP-DevBoard. The new firmware binary is in the TULIP4041-P2 build directory again (the .uf2 file).

Latest changes:
- serial port connects and disconnects are reported in the CLI
- PILBox connect status changes are reported in the CLI
- TRANSMIT ERR still occurs when there is a serial connection but no virtual IL device (PILBOX status is TDIS). This is intentional
- The HP-IL scope now shows the tracer sample counter for better correlation. There may be some jitter

About the trace counter: this is generated in real time for each HP41 T0-T0 cycle, even when the tracer is not connected, disabled or when samples are filtered. The shown trace samples lag behind the calculator activity.

Have fun and let me know your feedback.