[Suggestion][Editor] Zombie Counter

[GigaLem]

To paste from the Lemmings forum discord

I'm surprised a zombie counter hasn't been added to the editor, it would probably make it easier to track so I don't have to use the level validator
like the editor telling me the number of zombies I've put into a level

Like the editor doesn't tell me how many things I've selected in the original editor, so I can't tell how many zombies I have if I had them selected which makes things difficult for me to tell so I often have to resort to the level validator to do the math.

[namida]

Implemented in commit d9c65fb.