xnumpy: Use imgroi's find_contours in place of generate_contour_fast.
xnumpy: Use imgroi's find_contours in place of generate_contour_fast.

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