Add convenience constructors to client-side Date+NumberRenderer (#13334)

Change-Id: I61904c17e625d9910a56c7c57ec41032eed5a352

client/src/com/vaadin/client/ui/grid/renderers/DateRenderer.java

@@ -31,14 +31,25 @@ import com.vaadin.client.ui.grid.Renderer;
  */
 public class DateRenderer implements Renderer<Date> {
 
-    private DateTimeFormat format = DateTimeFormat
-            .getFormat(PredefinedFormat.DATE_TIME_SHORT);
+    private DateTimeFormat format;
 
     // Calendar is unavailable for GWT
     @SuppressWarnings("deprecation")
     private TimeZone timeZone = TimeZone.createTimeZone(new Date()
             .getTimezoneOffset());
 
+    public DateRenderer() {
+        this(PredefinedFormat.DATE_TIME_SHORT);
+    }
+
+    public DateRenderer(PredefinedFormat format) {
+        this(DateTimeFormat.getFormat(format));
+    }
+
+    public DateRenderer(DateTimeFormat format) {
+        setFormat(format);
+    }
+
     @Override
     public void render(FlyweightCell cell, Date date) {
         String dateStr = format.format(date, timeZone);

client/src/com/vaadin/client/ui/grid/renderers/NumberRenderer.java

@@ -31,7 +31,15 @@ import com.vaadin.client.ui.grid.Renderer;
  */
 public class NumberRenderer<T extends Number> implements Renderer<T> {
 
-    private NumberFormat format = NumberFormat.getDecimalFormat();
+    private NumberFormat format;
+
+    public NumberRenderer() {
+        this(NumberFormat.getDecimalFormat());
+    }
+
+    public NumberRenderer(NumberFormat format) {
+        setFormat(format);
+    }
 
     /**
      * Gets the number format that the number should be formatted in.