AP_NavEKF3: remove storedRange member variable if rangefinder measure…

[peterbarker]

…ments disabled

Board               blimp  bootloader  copter  heli  iofirmware  plane  rover  sub
Durandal            -32    *           -16     -16               -24    -24    -16
KakuteH7-bdshot     -104   *           -112    -104              -104   -112   -112
MatekF405           -72    *           -72     -72               -64    -16    -64
Pixhawk1-1M-bdshot  -96                -96     -88               -88    -24    -88
iomcu                                                *                         
revo-mini           -72    *           -72     -64               -64    -24    -64

We do need to come back and clean up these defines. We should have one define for "do we store rangefinder measurements?" (which we have), but we should also have a "can we directly fuse rangefinder measurements?" and "can we provide rangefinder measurements for optical flow fusion?"

At the moment we essentially only have one define controlling all of these things (AP_RANGEFINDER_ENABLED)

[khancyr]

LGTM

EK3_FEATURE_RANGEFINDER_MEASUREMENTS vs AP_RANGEFINDER_ENABLED is confusing even if they are the same for now