Add new ol.source.WMTS#getMatrixSet api function

src/ol/source/wmtssource.js

@@ -71,6 +71,12 @@ ol.source.WMTS = function(options) {
    */
   this.layer_ = options.layer;
 
+  /**
+   * @private
+   * @type {string}
+   */
+  this.matrixSet_ = options.matrixSet;
+
   /**
    * @private
    * @type {string}
@@ -92,7 +98,7 @@ ol.source.WMTS = function(options) {
   var context = {
     'layer': this.layer_,
     'style': this.style_,
-    'tilematrixset': options.matrixSet
+    'tilematrixset': this.matrixSet_
   };
 
   if (requestEncoding == ol.source.WMTSRequestEncoding.KVP) {
@@ -253,6 +259,15 @@ ol.source.WMTS.prototype.getLayer = function() {
 };
 
 
+/**
+ * @return {string} MatrixSet.
+ * @api
+ */
+ol.source.WMTS.prototype.getMatrixSet = function() {
+  return this.matrixSet_;
+};
+
+
 /**
  * @return {string} Style.
  * @api