Some items (like PipeBomb) are a class in both CfgMagazines and
CfgWeapons. BIS_fnc_invRemove uses weapon first, so that is why the
magazine was not being removed. Using config instead of string avoids
this problem.
It was not possible to sell a backpack from your gear or vehicle.
Added option to sell from gear. Sell backpack from vehicle is still not
possible currently due to Arma limitations.