NumberInput 1

This version of the NumberInput project adds functionality to the conversion engine and demonstrates simple buffer management in the 
controller class.  

A commitComposition method is added to the controller class. It is necessary to implement this method in order to commit an active input 
session based on certain user actions.

Next, the InputEngine class is added.  The demo uses a separate class for managing the input engine in order to again illustrate how 
certain "resources" can shared amongst all of your input controllers, and to emphasize modularization.

