ZF-2746: Zend_Form should implement Zend_Validate_Interface

Description

Zend_Form should implement Zend_Validate_Interface, and already does -- with the exception of type-hinting on the isValid() method. Removing that and putting the type checking into the method itself would allow Zend_Form to implement Zend_Validate_Interface, thus allowing it to be used as an all-purpose validator for data-sets -- which could allow swapping it in where Zend_Filter_Input has been used previously in models.

Comments

Committed to trunk and release branch