refactor(NgControl): erase redundant state flags
refactor(forms): remove scope event communication between controls
fix(forms): store models instead of controls within the collection of errors
fix(forms): consider forms as pristine only when all the inner models are non-dirty
refactor(forms): add return types and noop values for boolean getters
refactor(NgValidator): change interface and variable names
feat(core_dom): introduce NgElement
refactor(forms): use NgElement instead of dom.Element
refactor(NgModel): remove unused form code
chore(NgModelValidators): add ng- prefix to all validator classes
feat(NgModel): introduce parsers and formatters
fix(NgModel): ensure DOM value changes are only applied during scope.domWrite
feat(forms): append valid/invalid CSS classes for each validator on all controls