Mutation callback (#444)

* modification observer initials

* add debouncer to callback execution

* change feature name

* update

* code improvements

* tslint fixes

* use debouncer from utils

* add types

* upgrade

* fix

* update

example/example.html

@@ -226,6 +226,9 @@
       },
       onReady: function(){
         saveButton.click();
+      },
+      onChange: function() {
+        console.log('something changed');
       }
     });