Create mesh: add information message
@jean-marie.kerloch If there are two islands and one of them is drawn on the contour of the domain, create mesh won't work. It's OK for us because we never will have an island overlaid on the contour. So we should add this information message for the user:
If he has drawn an island on the contour: "Modify your contour: an island can't be drawn overlaid on the contour."
Edited by Sophie Bacchi