Epic #63846

Updated by Christian Kuhn over 9 years ago

Remove dependency to the parent object (@FormEngine@) in all form element classes. 
 All form classes get the @FormEngine@ injected and use methods of this class. 
 Our goal is to remove this dependency and cleanup the @FormEngine@ class as much as possible. 

 At the moment, the main FormEngine class and the sub element render classes like "InputElement" are tied together that the sub classes get the according FormEngine injected and call methods on this parent class very often. This is codewise ugly and should be resolved. Having the sub classes independent from FormEngine with a clean interface will show its dependencies much clearer.