Add serializers to public sandbox to allow export to glTF in inspector
Add serializers to public sandbox to allow export to glTF in inspector

sebavan/Babylon.js,jbousquie/Babylon.js,sebavan/Babylon.js,NicolasBuecher/Babylon.js,BabylonJS/Babylon.js,NicolasBuecher/Babylon.js,NicolasBuecher/Babylon.js,jbousquie/Babylon.js,Kesshi/Babylon.js,RaananW/Babylon.js,BabylonJS/Babylon.js,Kesshi/Babylon.js,RaananW/Babylon.js,sebavan/Babylon.js,jbousquie/Babylon.js,RaananW/Babylon.js,BabylonJS/Babylon.js,Kesshi/Babylon.js