hardware divider supports up to 8S, make it so in the code as well.
re-enable hardware i2c; update NVIC priority to use  define from CMSIS instead of magic 0x500 number
remove unnecessary averaging of PWM/PPM rc input
Merge remote-tracking branch 'multiwii/master'

Conflicts:
	src/board.h
	src/drv_timer.c
	src/mw.c
	src/sensors.c