hideHints to hide all hints. addresses: usablica#564 and usablica#587

Author: afshinm

intro.js

@@ -1216,7 +1216,6 @@
   function _removeHintTooltip() {
     var tooltip = this._targetElement.querySelector('.introjs-hintReference');
 
-
     if (tooltip) {
       var step = tooltip.getAttribute('data-step');
       tooltip.parentNode.removeChild(tooltip);
@@ -1320,6 +1319,22 @@
     }
   };
 
+  /**
+   * Hide all hints
+   *
+   * @api private
+   * @method _hideHints
+   */
+  function _hideHints() {
+    var hints = this._targetElement.querySelectorAll('.introjs-hint');
+
+    if (hints && hints.length > 0) {
+      for (var i = 0; i < hints.length; i++) {
+        _hideHint.call(this, hints[i].getAttribute('data-step'));
+      }
+    }
+  };
+
   /**
    * Add all available hints to the page
    *
@@ -1714,6 +1729,10 @@
     hideHint: function (stepId) {
       _hideHint.call(this, stepId);
       return this;
+    },
+    hideHints: function () {
+      _hideHints.call(this);
+      return this;
     }
   };