Replace all fastDigitalRead/Write() with READ/WRITE()
Define SCK_PIN, MISO_PIN, MOSI_PIN in pins.h if not already defined in the pins_*.h files.
Remove these conditional pin definitions from the pin-files. They are now always defined.
Define separate sets of SPI-pins for AT90USB with and without Teensy support in fastio.h.
Likely this was the main reason for all that confusion about the AT90USB-SPI pins.
