Fixed bug that caused the cooling fan PWM frequency to be 165kHz. It is
now 25kHz.
Fan RPM is now included in the web interface status response (thanks
zpl).
Many more error messages are now reported to the web interface as well
as the USB interface.
Interrupt-driven network timer task to better cope with slow SD card
writes (thanks zpl)
Module SamNonDuePin is now used for all digital and PWM pin I/O.