This makes it a little easier to discover recipes, since you now
generally don't have to get the exact count right anymore; just
make sure you at least have enough.
- Make node match operate on only one of node or stack, depending
on whether node defers to stack via is_stack_only. This should
hopefully prevent future pummel recipe issues.
- Add new core stack API. Needs to be deployed in a lot of places.
- Start work on system for allowing flammable containers; they
eject their potentially non-flammable contents.
Appears to work with existing functionality.
Next step will be to rework pummel to use a "recipe" system and
reuse most of the useful parts of the crafting system.
