Added isFirst, isLast methods.
Added isFirst, isLast methods.

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