Add FeatureNode implementation

CityDoctorParent/Extensions/CityDoctorGUI/src/main/java/de/hft/stuttgart/citydoctor2/gui/tree/CityObjectNode.java

@@ -4,7 +4,7 @@ import de.hft.stuttgart.citydoctor2.datastructure.CityObject;
 import de.hft.stuttgart.citydoctor2.gui.CheckStatus;
 import de.hft.stuttgart.citydoctor2.gui.Renderer;
 
-public class CityObjectNode extends Renderable {
+public class CityObjectNode extends Renderable implements FeatureNode{
 
 	private final CityObject co;
 
@@ -33,4 +33,9 @@ public class CityObjectNode extends Renderable {
 		renderer.render(co);
 	}
 
+	@Override
+	public CityObject getFeature() {
+		return co;
+	}
+
 }