nanshe/nanshe/expanded_numpy.py: Changed `index_at_pos` to use `numpy.roll` instead of setting up a transpose as it is faster.
nanshe/nanshe/expanded_numpy.py: Changed `index_at_pos` to use `numpy.roll` instead of setting up a transpose as it is faster.

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