Make camping less attractive

[otizonaizit]

Several ideas. We could start with the simplest:

General idea: Food pellets that lay under a defender' shadow (±5?) for too long (15×4 turns?) disappear and are randomly relocated

Implementation:

• Add a food_lifetime mapping { food_coord : eta } in game_state, which is initialized with eta == 15×4
• In play_turn loop through the food and create a new mapping food_lifetime
• Within the loop, if a food pellet is within one or two defender's shadow set eta = eta - 1.
• If eta==0: relocate food
• NTH: analogue to other events, an event FoodRelocated could be generated for the viewers to consume
• NTH: make something intelligent in viewer debug mode
• At the end of the loop, reset game_state['food'] and game_state['food_lifetime']