ZF-9914: Zend_Form - an alias for method: ->isErrors()

Description

It would be much nicer to do somethin like $form->hasErrors() than $form->isErrors(). It's just sounds a bit strange. For the backward's compatybility i propose to leave the old naming and create an alias for this method.

Comments

Scheduling for next minor

Patch with updated tests attached.

Fixed on trunk (25200) and release-1.12 (25201)

Thanks to Marc!