Wind speeds should not be uniformly distributed. This switches to a
Weibull distribution which allegedly (see the bug) is good enough.
Experimentally that seems true as well, though I know nothing about how
wind works irl. This at least looks like it'll generate reasonable
variation in missions while keeping the 1st through 3rd quartile
behaviors from getting out of hand.
I'm very uncertain about the scaling factor aspect of this. Naively the
wind speeds at different altitudes ought to be somewhat correlated, but
I'm not sure how much, and whether this kind of scaling is at all the
right way to do it. As before, meh, close enough?
Fixes https://github.com/dcs-liberation/dcs_liberation/issues/2861.
73e0cbe182