Thanks and some small enhancement requests

[Michael-F-Ellis]

Thanks for creating this! I discovered it yesterday and it's already helped clarify several questions I had about the PIO's operation. It's especially helpful that you've included scripts for all the SDK examples.

So far I'm using the monitor and fifo observer clients. They work very well. The docs and command line help are complete and easy to follow. It's clear you've put a lot of skillful, diligent work into this project.

May I offer a few small enhancement requests for the monitor program?

1. Ability to edit and re-run previous command lines. Maybe use Jline3?
2. Option to display clock cycle counts on each line of trace output.
3. Option to limit or filter trace displays, e.g run 100 cycles but only display the last 10.

[byteit101]

I have implemented #1 on my (WIP) fork: https://github.com/byteit101/pio-debugger-emulator