An attempt to alleviate crashes in light of some conflicts created with the major update.
### Changes:
- Changed `LayerRegistry` to extend `Layers` so mods that reference internal layer Identifier fields at their previous location will not cause a crash (except for renamed/removed fields).
- Reverted layer `boss_bar` to `bossbar` because it was actually consistent with how Mojang calls it.
Developer information
Projects on Modrinth are automatically available through a Maven repository for use with JVM build tools such as Gradle.
maven { name = "Modrinth"; url = "https://api.modrinth.com/maven" }
