Add simple survival system

Animals will only eat/drink from the position they currently are on
adding to their nutrient/water supply. Every cycle their supply is
reduced by their requirement. If their supply reaches 0 they die.
Plants/Lakes are just stationary water/nutrient providers.

Very ineffiecient implementation nesting loops for their positions, just seeing
if it works.

Currently very unbalanced. All animals die within seconds, increase
supply size and/or number of lakes/plants to balance.