To have proper low power mode, need to configure all unused pins in input mode, so need to have them available.
This allows you to register ExtInt on the MMA interrupt pin.
All board config macros now begin with MICROPY_HW_. Renamed PYBv10 to PYBV10, since macros should be all uppercase. Made SDCARD_DETECT configurable in mpconfigport.h, so that the SD detect pin can be easily configured.