EKF2: reset position by fusion

[haumarco]

Solved Problem

When the external position reset gets triggered we can now fuse the new position as a "normal" measurement. Therefore the position error (estimate-position on map) gets included in the other states and mainly the wind can be better estimated. For large jumps we still reset the position to ensure we dont induce a really strong wind estimate. Also adjusted the "set global origin" possibility before takeoff during GNSS denied conditions.

Alternatives

We could also, reset the position and fuse the "measurement" with a high variance. The estimated position would then perfectly align with the sent measurement position but the effects on the other states would not be as harsh for large position jumps (previous estimate / sent measurement).