Decouple sandwich-prep & meat-cooking

This reduces the skill & time needed for sandwich-prep, removes the heat requirement (but not the cutting), calls for cooked meat rather than raw, and makes the meat/cannibal sandwiches reversible since there's no
reason you couldn't take the meat off the bread and eat them separately.

If there's a problem regarding rotting and disassembly, well, we'll find out and fix!