An experiment with implementing L-systems.
Be careful with the iterations counter, some of the systems grow more than exponentially in instructions, so start with low values then increase one at a time.
To do: a way of allowing users to enter their own production rules, axiom, etc. or play with the existing setups - at the moment these are loaded from an XML file. Also do something to spread the iteration calculation over frames so the player doesn't just hang when the sequence gets huge.