Added zoom handler.
Added zoom handler.

bigspotteddog/envisionjs,notepad104/envisionjs,RobertoMalatesta/envisionjs,notepad104/envisionjs,bigspotteddog/envisionjs,HumbleSoftware/envisionjs,notepad104/envisionjs,RobertoMalatesta/envisionjs,RobertoMalatesta/envisionjs,HumbleSoftware/envisionjs