Refactor injection site finder

[adamltyson]

cc @FedeClaudi

[adamltyson]

@FedeClaudi When you get a minute, could you confirm that this refactored version still does what you expect?

So far done:

• Remove dependency on amap (by moving functionality to imlib).
• Remove dependency on vtkplotter by getting largest connected component using scikit-image.
• Reduced amount of code by moving a lot of "standard" functions to imlib.
• Allow logging to be onto to console (to file optional)
• Format with black

Still to do:

• Add tests (also in imlib)
• Generalise to other pixel sizes, orientations etc
• Remove hard-coded filenames (interface better with amap output directory/log file)
• Add different segmentation strategies (manual, semi-automatic).