Forms: RadioList separator is not rendered after last control (it is just separator)
Forms: RadioList: added support for wrapper instead of separator
Forms: removed parameter $size form SelectBox constructor

To be consistent with 00b6842b3edec96ca0002d3925c66b152009239e
Form: SelectBox: duplicated items are allowed
Forms: added ChoiceControl & MultiChoiceControl
Forms: refactoring of SelectBox, MultiSelectBox and RadioList; they are ChoiceControl and MultiChoiceControl descendants

BC break: MultiSelectBox is no more SelectBox descendant
Forms: added CheckBoxList