Allow segmentation based on pathing

It would be incredibly valuable to allow the creation of a segment of visits/visitors who saw Page X and THEN Page Y rather than just those who saw both in whichever order. Essentially creating a segment of people who followed a certain path, then seeing what else they did.

If we wanted it to REALLY rock, we'd want to be able to base the segment on both the fallout conversion AND the immediate next page. 

E.g. 

Segment = Visits who saw Page X then immediate next page was Page Y

or

Segment = Visits who saw Page X and later saw Page Y

Right now we can only do 

Segment = Visits who saw Page X and Page Y (in either order)