deleting a layer should need a confirmation popup

[imi]

(no text)

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Imi:

There is not a hotkey to delete a layer. So it is very unlikely that "delete layer" is hit by accident.

Adding it as optional with those kind of "[ ] Do not bother me again" - stuff to not annoy other users would be good.

Another option is to include the delete layer in the undo-buffer, although this would be a serious memory impact.

[anonymous]

Now, an one-time-message asks the user to continue.