autotest: added some hints to sim_arduplane.sh
autotest: expand the comment a bit more
AP_InertialSensor: always sample at 200Hz in MPU6000

this changes the sampling to 200Hz regardless of requested rate, and
it is downsampled inside num_samples_available() using a shift. This
gives better noise resistance in ArduPlane.

This patch also makes it possible to update the filter frequency while
running, which is very useful for bench testing with a vibration
source
AP_InertialSensor: removed unused new_data_available() and temperature() APIs
AP_InertialSensor: added filter frequency support to PX4 driver
Fixed cosmetic typo in user display message

Corrected "it's" to "its". Just one of those grammar things that drives me crazy ;-)
AP_HAL: added run_debug_shell() hal.util method
HAL_PX4: added run_debug_shell() implementation for PX4
Plane: added shell command for px4

used to launch nsh for PX4IO firmware upgrades
Copter: removed use of ins.temperature()
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!