.3de is the particle/effect format used by SealEngine. Like the
ReignEngine's .pae, it is a text format describing an effect as a set of
emitters, but the two differ enough in design that .3de lives in its own
file (s3de.c) rather than being folded into particle.c.
This commit lays the groundwork:
- Parse .3de text.
- Integrate effect loading, playback, and caching into the existing
infrastructure.
- Apply the camera object's per-frame override to RE_camera.
- Play the companion sound asset.
Billboard and polygon-object rendering will be added separately.