ZF-5125: Marker Interface for UiWidgetElement Decorator


Implement a Marker Interface Pattern for the UiWidgetElement Decorator, that is in UiWidgetElement Form Elements we have to add a function "_checkWidgetMarkerInterface" that iterates over the decorators and throws an exception when no decorator with the UiWidgetElement marker interface is found (which leads to the concolusion that someone might try to use the ViewHelper for rendering, which does not work).


Will be implemented in 1.8 and constitute a small BC break, since current implementations that overwrite the ZendX_JQuery_Form_Decorator_UiWidgetElement have to also implement the ZendX_JQuery_Form_Decorator_UiWidgetElementMarker interface.