fix to crash from yawn
Full Re-work of battle system with generalised number of participants and more work offloaded to the participant code.  This should allow easy extension to 3 or 4-way battles.  Double battles will still pose a bit of an issue

Also added lots of bug catching to all the attack code to stop crashes people are getting in game
Added support for exp share
added config options allowRiding and allowPlanting
Coded in everstone