Fix bug in Quaternion.invert() and add Quaternion.difference
Fix bug in Quaternion.invert() and add Quaternion.difference
FortressBuilder/JOML,JOML-CI/JOML,FortressBuilder/JOML,JOML-CI/JOML,JOML-CI/JOML,roquendm/JOML,roquendm/JOML