This PR replaces recursive explosions with a new spreading engine: iterative explosions.
Should behave similarly, but also be more reliable, potentially faster.
Iterative explosions also support simple-explosion-esque directional explosion sounds/shake, and will now traverse Z-levels if the explosion is strong enough.
Also changes playsound() to transmit sounds across Z-levels. Uses BYOND's 3rd coordinate on /sound to make sound sound above/below the player if they're using headphones. Removed for now, can't get Z-falloff working right.
Fixes#2199.
changes:
Maps are no longer compiled in, instead loaded directly from the DMMs at runtime.
Z level defines have been moved from the config to map datums.
Unit tests now use typecaches.
DMMS now actually works.
DMMS has been updated slightly.
DMMS is now capable of loading simple lists of non-text types.
DMMS is now faster when loading many types without mapped in attributes and when loading area instances.
Asteroid generation is now defined on the map datum instead of being hard-coded in SSasteroid.
Holodeck presets are now defined on the map datum.
Atmos machinery now uses Initialize().
