[FEATURE] Add possibility to add entities

[wielandb]

Describe the solution you'd like It would be great if we could do something like editor.place_entitiy(id, x, y, z) just like we can do editor.place_block(id, x, y, z).

This would help with a number of requested features, like spawning boats at docks, spawning farm animals in farms, spawning a population etc., since a lot of interesting things in minecraft are considered entities.

I dabbled a bit myself in trying to implement this feature, but never could get it to work. :(