Main: ParticleSystem - logError instead of assert on null material
Main: ParticleSystem - logError instead of assert on null material

as this can happen during script parsing, which we dont want to abort

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