SITL: change default wind speed to zero

makes starting SITL easier for new users
autotest: added some useful test missions for ArduPlane
px4: fixed passing of EXTRAFLAGS for ArduCopter frame type
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
AP_Menu: fixed crash bug in strtok_r() handling

on PX4 this causes a hard fault in CLI menus
Copter: bug fix for auto_armed logic

Zero throttle when switching into an auto flight mode would cause the
motors to stop.
AP_Motors: remove auto_armed

redundant flag that was already held in the main code which is where it
belongs.
Copter: remove unused waypoint_valid function
Copter: remove unused nav_ok and alt_sensor_flag