Nudging an execution nudges down also nested executions

[rschnekenbu]

When nudging an execution with nested executions, the nudging command is applied to all elements, regardless of their container. The nested execution is then nudged when its nesting execution is nudged, so its relative position on the nesting execution is modified.

before

after

[cdamus]

@rschnekenbu I think I'm incidentally fixing this with my work on dragging and dropping nested executions for #411.

[rschnekenbu]

Ah, @cdamus , interesting! I was looking to improve the management of the MoveDownVisitor to make him aware of the already moved containers on which children are located in a relative manner (elements on a lifeline, execution on executions, etc).
That's perfect if you already take care of that issue in the context of another one ;)

[cdamus]

Yeah, sorry, I had already done exactly that.