Merge pull request #7 from pimoroni/experimental/py_decl_and_dir2uf2

Bump dir2uf2 and produce sparse filesystem builds

Merge pull request #4 from pimoroni/patch-default-modules

default.cmake: Enable Pimoroni common modules.

README: Add pinouts and details.

Both: Fix pins.csv for #3.

Merge pull request #2 from pimoroni/dir2uf2-and-refactor

Dir2uf2 and refactor