Infer lateral drag coefficient based on airFriction

See #996. Yay for pushBack and vector operations.

I'll test it later today. Wait for that before merging 
The only ammo which has positive airFriction has `simulation = "shotMissile";` of `simulation = "shotRocket";`. I check for `_airFriction > 0` just in case an addon messes this up.

The fixed coeficient of 0.0007 is equivalent to the old 0.35 for rockects traveling at ~ 500 m/s with a crosswind of 5 m/s.