* Externalize the Divisor for usBackPackWeight
A new ini value BACKPACK_WEIGHT_FACTOR is introduced to replace the hard coded 50.
The value goes from 1 to 250 and its default value is 50 as before.
* Refactor usBPPenalty into its own function GetBackbackAPPenaltyFromBackpack
The same code is also used in GetAPsCrouch as well as GetAPsProne
The intent of the change is to make sure that backpacks including their content
do not add an additional AP cost of +1. Now it checks if
the backpack weight is > ubBackPackWeightFactorForAPPenalty (default value 50).
The min exists to make sure that the AP cost does not become higher than previously.
Previously the bool fBackpackCheck was used to add +1 if there is any backpack.
But this also includes an empty tactical sling (backpack with 0.2 kg) and
therefore makes the item much less interesting to use.