Each snippet is the body of a function called once per round. It receives
me, enemy (nearest living enemy), enemies
(all living enemies), bullets (in flight) and grid, and
must return an array of two actions, carried out one after the other. Each action is
"left", "right", "forward" or "fire".
Anything else means wait for that step. Bullets fly 4 squares per step and
reach 10 squares. Last tank standing wins.