Desert facities needs to have a Zombie spawn on load

[JulienLaclaverie]

We need to use placeholders (like for the campfires) and remove them on square load to spawn zombies at facilites in precise places.

• [ ] Placeholder for 1 Zombie :
• [ ] Placeholder for 5 Zombie :
• [ ] Placeholder for 10 Zombie :
• [ ] Placeholder for 20 Zombie :

[SylvainMarty]

I put here the legend for all the placeholders we are using in the map tool to spawn things by the mod :

[JulienLaclaverie]

You should integrate your code to the city objects code to avoid multiple code that check the square, this would end up being a performance problem.

Though this would mean renaming city objects too.

[SylvainMarty]

This was tested on single and multiplayer and it's working ! Now, we only need to use the placeholders :-)