dcm-check was triggering after 10 bad headings but these did not need to
be continuous meaning if the vehicle was flown long enough it would
almost certainly trigger a dcm-check failure and land

this allows the range of the Lidar to be set by the user using
RNGFND_MAX_CM and RNGFND_MIN_CM

The functions in the mount lib didn't work anyway

Barometer climb rate must be -150cm/s ~ +150cm/s
This threshold is generous because we already use the inertial
navigation climb rate so this is just to catch cases where inertial nav
is very incorrect in it's climbrate estimates

This corrects a bug that allowed the waypoint speed to be set to zero

fixes issue in which now could be earlier than _last_update_xy_ms
leading to a large dt value and a sudden lean on takeoff

This will help prevent spurious alt disparity warning messages for copter

Issue discovered and fix contributed by Deadolous