breadth first traversal of the tree of nested graphs

[rat10]

Olaf Hartig provided a formalization as a means to better understand NNG. His formalization is very succinct and provides a good basis for further discussion. He illustrates a problem with basic graph patterns being returned multiple times when they occur in inner nested graphs (once for each nesting graph).
This is not surprising but nonetheless a usability problem. While his formalization assumes a depth first traversal of the tree of nested graphs, a breadth first traversal would provide a more intuitive result set. This needs to be implemented and tested.

[lisp]

as i understand the current implementation, it performs the breadth-first traversal.
this is to be tested and the option to effect the alternative will need to be implemented.