Allow spacing changes between group and question

[benzea]

In the below example (which uses \vbox{\raggedright } for alignment), the spacing between the choicegroup question text and the header line is way too small.

We should probably insert some spacing there, it is not clear to me whether that should be the row spacing, or possibly some other spacing.

[benzea]

There is something fishy there … rangearray/choicearray take an argument to insert a header, but don't actually handle displaying it.

That really does not make sense, the logic needs to be moved into sdapsclassic (i.e. sdapslayout is not responsible for headers/grouping).

As for the spacing, that is "just" the normal spacing for the section. Probably still makes sense to just add an option to insert extra spacing.