Algorithmic complexity of difflib

[dg-pb]

@pf_moore

do you intend to publish the resulting code as a library on PyPI and/or submit it as a PR to the stdlib?

Intent was always to improve difflib. There is a standing PR which adds composability so that new matchers can be used with all utilities there. So that is the 1st step. After that is done, I had 2 trajectories:

1. PR1 for improved utilities and a bit of preparation, then PR2 with SAM based matcher above.
2. Improving existing SequenceMatcher so that the issues with default matcher are reduced to a minimum. See Improvement on current `difflib.SequenceMatcher` algorithm

Will see how this goes. From my experience things are moving rather slowly when it comes to algorithms.