IPython magic only import things in `"__all__"`
IPython magic only import things in `"__all__"`

Make the IPython cell magic only import things in `"__all__"` when `"__all__"` exits.
da-woods/cython,scoder/cython,da-woods/cython,scoder/cython,cython/cython,ChristopherHogan/cython,cython/cython,ChristopherHogan/cython,scoder/cython,cython/cython,da-woods/cython,ChristopherHogan/cython,cython/cython,scoder/cython,da-woods/cython