Add support for all objects types as tilemap children

[cosmiccoincidence]

Summary

All object types will eventually need to be under or tied to the tilemap.

The first reason for this is that we eventually want to be able to move/rotate a tilemap and have all items, entities, and even vfx like bloodstains that appropriately stay on their position relative to the tilemap despite the tilemap moving through space.

The second reason for this is we want to be able to save a snapshot of a tilemap at any point during a game round and have the save file accurately save object orientations (including items, entities, & vfx) but also object states (like a jukebox left playing, an airlock malfunctioning, etc).

(This task obviously isn't as simple as making these objects children of the tilemap as the title implies.)