Reloading a saved game while falling prevents damage in some cases

The issue #4049 (closed) was not fixed completely. I still can reproduce it in some cases in both upstream master and 0.43 release.

1. If you restart a game and load save in which player is falling instead of just reload, a fall damage will not be applied. If you load this save again, damage will be applied, so I guess there is some missing initialization during first session.
2. If you manage to catch a moment when the player is almost reached the ground, after reload OpenMW will consider player as standing on ground and will not apply damage.

(RM-4411 from redmine: created on 2018-05-05 by Andrei Kortunov, )