DataFlash: added file based 'dataflash' logging
RangeFinder: fixed a warning
AP_HAL: added register_io_process()

this is used to register a low priority IO task. Used for file IO in
DataFlash_File.cpp
Rover: fixed logging for new API
Copter: fixed logging for new API
Plane: fixed logging for new API
Copter: made more variables static
Plane: added PX4 flash logging
Rover: added PX4 flash logging
CPUInfo: test NaN and Infinity printing
autotest: added --cli option to dump_logs.py
build: fixed heli-hil and quad-hil copter builds