Adding Rigid Rotor model

[ajarifi]

I add a 3D rigid rotor model #8 . I hope it is enough for the paper.
Of course, it is very simple and I do not add many things.

By the way, I had a problem when running include("./developer/docs.jl").
the error message is given below.
Other than that, I think there is no problem.

ERROR: LoadError: ArgumentError: Package SparseArrays does not have SuiteSparse_jll in its dependencies:

• You may have a partially installed environment. Try Pkg.instantiate()
  to ensure all packages in the environment are installed.
• Or, if you have SparseArrays checked out for development and have
  added SuiteSparse_jll as a dependency but haven't updated your primary
  environment's manifest file, try Pkg.resolve().
• Otherwise you may need to report an issue with SparseArrays

[ohno]

The number of arguments was wrong. 9521c15

- Antique.ψ(::RigidRotor, ::Any, ::Any, ::Any)
+ Antique.ψ(::RigidRotor, ::Any, ::Any)

[ohno]

I updated developer tools. 54fde9a

Please uncomment some lines in docs.jl. We can run Pkg.instantiate() and Pkg.resolve().