Add support for storing the learned policy

[GoogleCodeExporter]

Add some way to persist a policy across experiments. The idea is being able
to interrupt the experiment without losing all already learned knowledge.

This would also allow for later on loading the learned policy and

- continue learning from an advanced starting point
- just evaluate the policy, to perform a learned behaviour

Original issue reported on code.google.com by ricardok...@gmail.com on 29 Jun 2009 at 12:01