fixed bug: problem with editing size and coordinates of cloned controls

(the attributes of the original control were set)

de.bmotionstudio.gef.editor/src/de/bmotionstudio/gef/editor/attribute/AbstractAttribute.java

@@ -55,10 +55,8 @@ public abstract class AbstractAttribute implements IPropertySource, Cloneable {
 	}
 
 	public void addChild(AbstractAttribute atr) {
-		if (!getChildren().containsKey(atr.getID())) {
 		getChildren().put(atr.getID(), atr);
 	}
-	}
 
 	public Boolean hasChildren() {
 		return !getChildren().isEmpty();