Display invalid watersheds
Display invalid watersheds

Display all generated watersheds instead of clearing them if the validation
step fails.

Connects #1657

kdeloach/model-my-watershed,WikiWatershed/model-my-watershed,WikiWatershed/model-my-watershed,kdeloach/model-my-watershed,kdeloach/model-my-watershed,kdeloach/model-my-watershed,WikiWatershed/model-my-watershed,WikiWatershed/model-my-watershed,WikiWatershed/model-my-watershed,kdeloach/model-my-watershed