De-select shortcut (esc)

Add a behavior for the Escape (Esc) key.

When my maps are full of objects it can become a somewhat difficult task to find an empty space to click in order to de-select the object I've finished working on (so then I can scroll the mouse to zoom out and look at the big picture).

I find myself often trying to press Esc to de-select the object, but it only ever opens a Menu with the options Resume, Settings and Exit.

Would be nice if "Esc" could just de-select an object. And then if pressed again, with no object selected, open the menu.