Destructible crates

Short version: instead of rolling a number between 4 and 20, someone set it up so that it rolled 4d20, and compared that to your strength. Unsurprisingly, this made crates able to withstand the Fist of the North Star and required some luck combined with a sledgehammer to smash them.

They are now a little more reasonable. You'll need 10 str to even have a chance of breaking them with your bare hands, but weapons will help.

Also fixes #2703, which I tested with a flatbed truck. TRUCK WINS - FATALITY.