UI consistency "Rendering order..." to "Symbol levels..."

Author: m-kuhn

src/ui/qgsrulebasedrendererv2widget.ui

@@ -11,7 +11,16 @@
    </rect>
   </property>
   <layout class="QVBoxLayout" name="verticalLayout">
-   <property name="margin">
+   <property name="leftMargin">
+    <number>0</number>
+   </property>
+   <property name="topMargin">
+    <number>0</number>
+   </property>
+   <property name="rightMargin">
+    <number>0</number>
+   </property>
+   <property name="bottomMargin">
     <number>0</number>
    </property>
    <item>
@@ -134,7 +143,7 @@
      <item>
       <widget class="QPushButton" name="btnRenderingOrder">
        <property name="text">
-        <string>Rendering order...</string>
+        <string>Symbol levels...</string>
        </property>
       </widget>
      </item>