[Feature] show head of Kurve even when a whole is being created

[marko-curlin]

When a hole is being created in a line, it would be useful to show the head. If you're close to a wall, for the split second the hole is being created, you loose sight and can lead to wall collisions.

[maechler]

@marko-curlin Thanks for the feature request! That's a good idea, I think we could add this. But I also think it's not that critical as you should already be able to steer the curve when it's invisible.