Add a new Item raw type and entity type, with preliminary, basic support
for food. There's a really frustrating toml-rs bug that prevents writing
these nicely as toml right now, so I also added support for mixing JSON
and TOML in a single config dir
Add a system for statically-included entity raws (which necessitated
making a deserializable existential Color struct) and test it out by
initializing the game (for now) with a single on-screen gormlak.
Implement a global map of entities, which allows referencing by either
position or ID and updating the positions of existent entities, and put
the character in there.
