Replace text on all selected shape by "..."

[MarcHulsebosch]

Issue
When re-using an existing slide as a template for a new one, it is often helpful to remove all text in one go, to ensure no text remains from the old slide by accident. However, when you use the button "remove all text", this deletes textboxes (or maybe sometimes makes them hard to find if they're not really deleted?)

Solution
In addition to the button to remove all text, it would be great to have a button that replaces all text in each shape simply by "..."