Add entity querying to World Interaction API

[mezzodrinker]

Originally reported here: https://www.mobtalker.net/forums/viewtopic.php?f=18&p=4763

It would be nice if you could query for entities via the World Interaction API. This way, making the entity being talked to react to whatever is around it could be used even more, for example if a Creeper should react to an Ocelot in the vicinity.