remove variable observation_space since it is not really used anywhere and adjust examples in doc to match the code

Refactoring: add return types for ObservationBuilder.get(self, handle: int = 0) and ObservationBuilder.get_many(self, handles: Optional[List[int]] = None)

Refactoring: delete new_position from TreeObsForRailEnv and use flatland.core.grid.grid4utils.get_new_position instead

local grid observations will not be updated. It was never used for the challenge and is not well suited for the task at hand.

now detecting malfunctioning agents
now detecting slowest fractional speed

fixed formatting

now detecting malfunctioning agents
now detecting slowest fractional speed

and render custom obvsercations

Now turns with the agent, encodes local information which can easily be enhanced by predictions, distance map and other things.

Now turns with the agent, encodes local information which can easily be enhanced by predictions, distance map and other things.

Agents now get warned about conflicts when other agents have reached their target and are in the way.