WANTED: writing new configs to a binary file

[bsstephan]

Writing a config would be an awesome tool in the toolbox. It could then be something that is picotool'd back onto the board, or customized stock images made for mass production.

[bsstephan]

Just to clarify, I just want to be able to create a new .bin file suitable for picotool load, I don't think we need to invoke picotool for the user unless we start getting more complicated tools.

[bsstephan]

v0.3.0 introduces modifying configs and writing them to files, but I'm going to keep this open because the editor cannot yet create a new config from zero. I also think there could use to be another tool or two for combining files, but maybe I'm overthinking things.

[bsstephan]

v0.5.0 might have accomplished this, but I'm leaving this open for a bit to facilitate more testing.