Rover: major restructuring

this removes a lot of the old arduplane code, and renames a lot of
variables.

This will need a lot more testing and fixup before being usable
Rover: rename Attitude.pde to Steering.pde
Rover: added filter to auto steering, and fixed throttle pid
Send FS state to gcs for AP
Send FS state to gcs for AC
Send FS state to gcs for AR
Rover: cleanup parameter names and remove dead parameters
PID: change to float input/output

this makes the PID library a bit more flexible for smaller range
numbers. Note that this library is used on ArduPlane and Rover, not
Copter
autotest: fixed rover parameters for new config
Plane: fixed target speed reload on landing

thanks to Doug for this fix!
autotest: allow sim_arducopter.sh to take mavproxy parameters
Plane: make CIRCLE mode hold altitude

this will prevent us losing a lot of altitude during the initial
failsafe phase
build: fixed etags target
Plane: update firmware version to 2.69
Tools: added build_all_px4.sh

this brings px4 into autotest
Plane: fixed an integer multiply error that caused poor altitude on landing 

the control of altitude between waypoints was broken due to an integer
overflow
AP_InertialSensor: expand register range in MPU6000 _dump_registers()
Plane: enable MAV_CMD_DO_DIGICAM_CONTROL
SITL: added SIM_GPS_TYPE control

for choosing what sort of GPS to simulate
SITL: added simulation of the original MTK GPS