Shunts on intern cells

[flo-dup]

Do you want to request a feature or report a bug? Feature / bug

What is the current behavior? There cannot be shunts between two intern cells

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem

1. Create network with 4 busbars and two couplers, each one linking two bus bars.
2. Link these two couplers together through a switch
3. Run single-line-diagram layout

What is the expected behavior? Cell detection works and diagram generated with proper coordinates, similar to this:

What is the motivation / use case for changing the behavior? Real case with shunts between intern cells