For the 3 ports that already make use of this feature (stm32, nrf and
teensy) this doesn't make any difference, it just allows to disable it from
now on.
For other ports that use pyexec, this decreases code size because the debug
printing code is dead (it can't be enabled) but the compiler can't deduce
that, so code is still emitted.
Cleaning up use of "pyb" module.
Moving the file to a new folder and updating the
makefile accordingly. New module created called
"board" to take over the functionality of the legacy
"pyb" module.
Updating outdated documentation referring to pyb.Pin,
to now point to machine.Pin.