An API to register particle factories on the client. Necessary for any mod that wants to even approach custom particles.

Forge: ParticleFactoryRegisterEvent (Forge makes ParticleManager.registerFactory accessible)
Fabric: ParticleFactoryRegistry

Additionally, a utility class similar to FabricParticleTypes would be appreciated, just so we don't need to extend DefaultParticleType. nvm, seems like it's pretty much useless

Weird, this should've been closed by #110. Anyways, yeah it's a thing now!