these were only being used in one place, and in that place were used
incorrectly!

its all in parameters now

this limits the sizes of the MAVLink buffers. It doesn't make a big
difference now, but it will matter when we update to the latest
mavlink code which has some very large packets

we now use the Stub version of the InertialSensor driver. In sensors
HIL we can now correctly drive the AHRS code.

should prevent occasional timeouts

this allows the user to select the MPU6000 filtering frequency

this lets the caller not need to know the underlying sample rate. They
just ask for what rate updates happen. 

This also changes the MPU6k filtering to be less than half the sample
rate

fix scaling problem on arducopter config tab. when linking is enabled

get rid of flight_mode_strings and cleanup unused code

switch to using ahrs for have_position

failsafe: hide element not needed
ap_limits back - beta
add new accel setup - beta
fix planner config screen exception
fix quickview desc/units if never been configured

starting at 1000 is a very bad idea - a petrol engine could cut out