The rangefinder handling doesn't handle sonar glitches like
locking on to reflections very well. We will remove the
rangefinder as an input to the controllers until we can do a
more robust implementation.
This is to match a change made to Copter.
It might be relevant to sub in that users may wish to have asymmetrical descent and ascent rates.
New parameters named:
PILOT_SPEED_UP (technically renamed PILOT_VELZ_MAX)
PILOT_SPEED_DN
Removed parameter PILOT_VELZ_MAX (technically renamed to PILOT_SPEED_UP).
Modes impacted:
ALT_HOLD
CIRCLE
POSHOLD
Update a section in GUIDED mode but I don't think it is ever used but update just in case.
It will use the PILOT_SPEED_UP for ascending max velocity. For down it will check if
it is 0, if so then it will PILOT_SPEED_UP instead, if non zero it will use PILOT_SPEED_DN.
This retains current behavior and gives the flexibility to change it if desired.
The above behavior is less of a concern for Sub but to keep it consistent its been implemented it the same way.
