fixed Double box creation in DataEntryDialog to also accept null/Double instead of double only

java/com.sap.sse.gwt/src/com/sap/sse/gwt/client/dialog/DataEntryDialog.java

@@ -266,7 +266,7 @@ public abstract class DataEntryDialog<T> {
         return longBox;
     }
 
-    public DoubleBox createDoubleBox(double initialValue, int visibleLength) {
+    public DoubleBox createDoubleBox(Double initialValue, int visibleLength) {
         return createDoubleBoxInternal(initialValue, visibleLength);
     }