nanshe/advanced_image_processing.py: Refactored extract_f0 into estimate_f0 and extract_f0.
nanshe/advanced_image_processing.py: Allow returning F_0.
nanshe/advanced_image_processing.py: Drop unneeded variable name statement.
nanshe/advanced_image_processing.py: Drop bias as it is not an argument.
nanshe/advanced_image_processing.py: Correct how output is handled. Make sure results are still written into out.