setup.py: Try to add Cython as an install requirement so that pip will grab it.
setup.py: Try to add Cython as an install requirement so that pip will grab it.

DudLab/rank_filter,jakirkham/rank_filter,nanshe-org/rank_filter,nanshe-org/rank_filter,DudLab/rank_filter,jakirkham/rank_filter,nanshe-org/rank_filter,jakirkham/rank_filter,DudLab/rank_filter