This patch ads irq method to the pin object. Handlers
registered in the irq method will be kept as part of the
ROOT_POINTERS.
In order to resolve which pin object is the root of the
IRQ, the pin_find has been extended to also be able to
search up Pin objects based on mp_int_t pin number.
This also implies that the Pin.new API is now also supporting
creation of Pin objects based on the integer value of the
pin instead of old style mandating string name of the Pin.
All boards have been updated to use real pin number from
0-48 instead of pin_Pxx for UART/SPI and music module pins.
UART/SPI/modmusic has also been updated to use pin number
provided directly or look up the Pin object based on the
integer value of the pin (modmusic).
Pin generation has been updated to create a list of pins, where
the board/cpu dicts are now refering to an index in this list
instead of having one const declaration for each pin. This new
const table makes it possible to iterate through all pins generated
in order to locate the correct Pin object.
6e8a605500