[BUG] Propellant efficiency stored in bulletdata

[LiddulBOFH]

Currently propellant efficiency is being stored post-calculation in bulletdata. Since it is a weapon class specific variable, it should be checked when the weapon is fired, and not stored in the ammo.

It is currently like this: https://github.com/Stooberton/ACF-3/blob/master/lua/acf/shared/ammo/he.lua#L40

And instead it should look at the class of weapon that is firing the round, for the Efficiency variable.

[TwistedTail]

Fixed on e6b32c9.