nanshe/imp/segment.py: Explicitly use `numpy.float64` when wanted.
nanshe/imp/segment.py: Explicitly use `numpy.float64` when wanted.

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