allow scale to be two dimensional

add getScaleArray() method

test two dimension scale icons
test two dimension scale text

add example of icon and label scaling
use smaller icon and larger interval
test two dimensional scale icons
test two dimensional scale icons

rendering/cases/text-style/main.js

@@ -110,15 +110,23 @@ feature.setStyle(
 );
 vectorSource.addFeature(feature);
 
-// background and padding
+// two dimensional scale
 feature = new Feature({
-  geometry: new Point([-10, 0]),
+  geometry: new Point([100, 20]),
 });
 feature.setStyle(
   new Style({
     text: new Text({
-      text: 'hello',
+      text: 'mirror',
       font: '12px Ubuntu',
+      scale: [-1, 2],
+      rotateWithView: true,
+      fill: new Fill({
+        color: 'red',
+      }),
+      stroke: new Stroke({
+        color: '#000',
+      }),
       padding: [1, 2, 3, 5],
       backgroundFill: new Fill({
         color: 'rgba(55, 55, 55, 0.25)',