World island basics

Implemented all the objects.

Implemented the "Survivor" world adapter as a static world without any temporal dynamics (objects never vanish and supply unlimited amounts of everything).

Agent is always looking at closest object. It should thus be possible to implement a basic simpleagent-like agent in a world where different grid grid locations have different closest objects and some basic learning is possible.

Main problem left is fuglyness.

Structured objects and survival are two distinct world adapters so far. We'll want to merge them at some point, and introduce more complex scenes than "nearest object".
We should also move away from discrete grid-based locomotion once the agents can handle continuous movements.