Extensibility of DDAPI

[DecDuck]

Context: I'm looking into ways to build my Spellbind mod.

A way to add custom submodules (see #25) that transform mod-specific schemas.

Namespacing was definitely a good idea.

[DecDuck]

I'm thinking about a kind of structure rework (from a monolithic module) to something like this:

Pros:

• Mods can add custom handlers and then add their own DDAPI definitions
• Versioning available
• Validation from schema, so catching errors early on in the loading process (also making us maintain schemas)
  Cons:
• More work?
• ... I think I'm blind to the down sides because I made it up

[DecDuck]

Just a little context:

1. By "transform data" I mean expanding schema shortcuts (like when people put a single value for a single entry array), and stuff like that - no actual game processing.
2. "Hook game and load data" isn't a single script, it's probably closer to what DDAPI already does, with shadows all over the place.

[DecDuck]

Approach would also solve #24