Unique Origins

Added support for layers. For previously unsupported layers such as classes, will require setting everyone's origin on that layer (e.g. class) to something else then back to normal on existing servers, as the mod only tracks origin changes, and layers where no changes occurred since the mod was installed (default layer) or updated to this version (other layers) are considered to be unregistered.

Added the uniqueorigins command to query, set, or toggle filtering, for individual layers.