Removing an edge may give the impression the wrong edge has been removed

[gcoutable]

• I have checked that this bug has not yet been reported by someone else
• I have checked that this bug appears on Chrome
• I have specified the version :

• latest

• I have specified my environment :

• my computer: Windows

Screenshots

Issue-removing-an-edge.mp4

Steps to reproduce

1. Create two edges between two same elements
2. Remove the first edge created

Expected behavior

The remaining edge keeps its position

Actual behavior

The remaining edge take the position of the removed edge

[gcoutable]

Since many edges can be displayed between two same elements, a hidden issue is now visible.
This behavior is due to the way edge ids are defined. Among other parameters, we use the number of edges present in the diagram to calculate the id of an edge. Which explains the actual behavior.

To fix this issue we should rely on edge anchors instead of a counter to build edge ids.