tests/test_advanced_image_processing.py: Added test for extract_neurons using 3D data.
tests/test_advanced_image_processing.py: Added test for extract_neurons using 3D data.

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