Added hide property to View

Views now support a hide property which is the inverse of display.
This means two mutually exclusive views can be switched with a single bound property:

{{view "App.TextControl" hideObserveBinding="showInput"}}
{{view "App.EditButton" displayObserveBinding="showInput"}}

Show the edit box by setting showInput true, this will hide the edit button:
@set 'showInput', true