non-operative roundabouts

Created by: das-g

check whether (and make sure that) roundabouts in nonop_l (or which would belong in nonop_l)

• are present in the right layer (nonop_l) (already handled by b9a5b8c1 PR #583)
• aren't present in other layers (e.g. road_l) (already handled by b9a5b8c1 PR #583)
• are otherwise (e.g. concerning type and aggtype) treated analogously to operative roundabouts in road_l