Layers: Added serialization/ deserialization

src/core/Object3D.js

@@ -663,6 +663,13 @@ Object3D.prototype = Object.assign( Object.create( EventDispatcher.prototype ),
 
 		if ( this.matrixAutoUpdate === false ) object.matrixAutoUpdate = false;
 
+		if ( this.layers.mask !== 1 ) {
+
+			object.layers = {};
+			object.layers.mask = this.layers.mask;
+
+		}
+
 		//
 
 		function serialize( library, element ) {

src/loaders/ObjectLoader.js

@@ -865,6 +865,7 @@ Object.assign( ObjectLoader.prototype, {
 		if ( data.frustumCulled !== undefined ) object.frustumCulled = data.frustumCulled;
 		if ( data.renderOrder !== undefined ) object.renderOrder = data.renderOrder;
 		if ( data.userData !== undefined ) object.userData = data.userData;
+		if ( data.layers !== undefined ) object.layers.mask = data.layers.mask;
 
 		if ( data.children !== undefined ) {