Load method now checks if each property of a parsed .babylon file is defined before attempting to process.
Load method now checks if each property of a parsed .babylon file is defined before attempting to process.

Prior to this change exclusion of autoclear, lights, etc would cause loading to fail.

sebavan/Babylon.js,jbousquie/Babylon.js,Temechon/Babylon.js,BabylonJS/Babylon.js,abow/Babylon.js,NicolasBuecher/Babylon.js,Temechon/Babylon.js,BabylonJS/Babylon.js,Temechon/Babylon.js,abow/Babylon.js,Kesshi/Babylon.js,Kesshi/Babylon.js,Kesshi/Babylon.js,abow/Babylon.js,RaananW/Babylon.js,NicolasBuecher/Babylon.js,Hersir88/Babylon.js,jbousquie/Babylon.js,RaananW/Babylon.js,jbousquie/Babylon.js,RaananW/Babylon.js,Hersir88/Babylon.js,sebavan/Babylon.js,NicolasBuecher/Babylon.js,Hersir88/Babylon.js,sebavan/Babylon.js,BabylonJS/Babylon.js