Performance: Container mass/cost recalculation is not optimal

[ihsoft]

Today the mass/cost of the container is recalculated on every fixed frame, which is hugely ineffective. The mass/cost must be cached and updated by a request. The items in the container are not expected to change without a player action.

[ihsoft]

It's now only updating when the changes has actually happen. No wasted CPU on the part updated.