Various improvements to the generic View code
Among others:
* Added the 'page' argument to the simple.errorResponse call
* Pass the result of getEmptyKeyFields to edit() in create()
* Fix typo's in error responses
* Fixed a todo to properly redirect on create
* Made editPost return something when the form is not valid
* Added an _editGet hook
Patch by: Sverre Rabbelier
Reviewed by: to-be-reviewed