Pocketknives, etc., can cauterize now

Make pocketknives (and other knives) able to cauterize wounds now, giving the wilderness types a way to deal with bites.

Should realistically use more than 1 charge from a lighter, but on the other hand, you'd probably light something else on fire first and then use that on the metal.

Feel free to ignore until the massive item overhaul commit is merged, then I'll see what needs to be patched in this branch.