Also replace use of PINMUX_DEFAULT with PINMUX_UNUSED to prevent any
accidental pin changes. This caused user SPI to break internal SPI
flash on the Feather M0 Express.
Fixes#100
* Track status pin use by user code separately so it can take over the pins and then give them back.
* Switch to hardware SPI for APA102 on Gemma and Trinket.
* Merge microcontroller/types.h into microcontroller/Pin.h to better match approach going forwards.
This was done to allow greatly granularity when deciding what functionality
is built into each board's build. For example, this way pulseio can be
omitted to allow for something else such as touchio.
