Refactoring:

   * Start switching the brain logic to emitting actions
   * Introduce decision strategies for brains
   * Rectify action and attack handling --- spaghetti attack events are gone
   * Remove dead code
   * AgressiveWalker is next -> currently deactivated
Refactoring:

   * Entites are now a property of strategies
   * Add the hunt "strategy"
   * Attacked monsters fight back
   * Add an "attacked" method to entites
   * Refactoring: events always carry the sender as last argument
   * Refactoring: slightly more canonical treatment of heading (still not complete)
Refactoring:

   * A bit more refinement to the strategy system
   * Reinstate agressive walker, now also attacks back
   * Add healing logic to all monsters
   * Move healing to stats --- not good, but better ;)