Main: ParticleSystem - we can assume emitters are not NULL
Main: ParticleSystem - we can assume emitters are not NULL

also slightly simplify initialisation

OGRECave/ogre,OGRECave/ogre,paroj/ogre,OGRECave/ogre,OGRECave/ogre,paroj/ogre,OGRECave/ogre,paroj/ogre,paroj/ogre,paroj/ogre