Merge pull request usablica#225 from andragan/master

added onafterchange handler, and call it just before the end of _showElem...

Author: afshinm

intro.js

@@ -654,6 +654,10 @@
         window.scrollBy(0, bottom + 100); // 70px + 30px padding from edge to look nice
       }
     }
+    
+    if (typeof (this._introAfterChangeCallback) !== 'undefined') {
+        this._introAfterChangeCallback.call(this, targetElement.element);
+    }
   }
 
   /**
@@ -886,6 +890,14 @@
       }
       return this;
     },
+    onafterchange: function(providedCallback) {
+      if (typeof (providedCallback) === 'function') {
+        this._introAfterChangeCallback = providedCallback;
+      } else {
+        throw new Error('Provided callback for onafterchange was not a function');
+      }
+      return this;
+    },
     oncomplete: function(providedCallback) {
       if (typeof (providedCallback) === 'function') {
         this._introCompleteCallback = providedCallback;