abstract validator class
allow validate by validato class
move required vaidator to class
some error methods
remove debug
move equals validator to class
move in valuidator to class
move numeric validator to class
change validator class naming, move null validator to class
move regexp validator to class
move email validator to class
move not equals validator to class
Uncompartible changes: validator method return no values and must call Document::addError() method to add error into stack.
allow define own validator namespaces