Robert8888 patch choices

[robert8888]

Changing base field for DynamicArrayField adds choices to widget. (even if they are empty). source It could work without changing base to ChoiceField by just explicitly coping choices field to self.widget.choices like do it base class. But I changed to get validator inheritance as well.

Now widget checks that it have choices and this choices have not 0 length. If it get choices then it will render subwidget as Select option widget if not then it take TextInput or Textarea or custom. (But this custom have to be onn of select, input or textarea because of js script)