Fixes & reorg

Moved Julia code to own directory.
Julia code now runs properly after fixing a pass by reference error.
Cython code now doesn't pointlessly resolve landscapes, and uses the
hillclimber from the Julia implementation.
Misc

Added a show method for agents, fixed some indentation, fiddled with
data dumping.
Circularity

Julia doesn't handle circular refs very well, therefore Agents are no
longer used as keys in other Agents.