Build all 4 different boot_stage2 objects with SPI/2 and SPI/4 options.
Add a menu to the generic board to allow selecting between them.
Use the potato/4 boot2 for the Adafruit Feather until we have a better
version verified.
Fixes#42
Add support for Adafruit Feather RP2040 (8MB). Identified with a unique
USB PID so it displays properly once programmed one time. Moved LED to
pin 13 (per the website docs), but have no board to test.
Add over/underclocking menus, applied at boot. Use at your own risk, as
usual.
Add shims to allocate flash space for a filesystem (but not implemented
yet).
Add a "generic" RP2040 board
Some paths hardcoded to my custom toolchain build dir, will be updated
to a package.json tools setup soon.
https://github.com/earlephilhower/pico-quick-toolchain
Blink and Fade examples work (i.e. digitalWrite/analogWrite/delay).
Includes a discovery script which will detect RPI Picos in UF2 bootmode.
