Make connected components processing more compact

Connected components processing in compound nodes with hierarchical ports is complex and may generate excessive whitespace, as in this case:

This is probably due to which area the connected components are assigned to (in this case, the comments are in the center area, while the graph is in the south-east area) and how the areas are placed exactly.

This could be improved by recognizing when areas can be moved together. In this case, for example, it would be perfectly fine to move the SE area under the C area.