patch: add within-line color diff capacity
The `diff' command usually writes deletion in red and insertions in green. This
patch adds within-line colors, to highlight which part of the lines differ.
Lines to compare are decided based on their similarity ratio, as computed by
difflib SequenceMatcher, with an arbitrary threshold (0.7) to decide at which
point two lines are considered entirely different (therefore no inline-diff
required).
The current implementation is kept behind an experimental flag in order to test
the effect on performance. In order to activate it, set inline-color-diff to
true in [experimental].
Our full contribution guidelines are in our wiki, please see:
https://www.mercurial-scm.org/wiki/ContributingChanges
If you just want a checklist to follow, you can go straight to
https://www.mercurial-scm.org/wiki/ContributingChanges#Submission_checklist
If you can't run the entire testsuite for some reason (it can be
difficult on Windows), please at least run `contrib/check-code.py` on
any files you've modified and run `python contrib/check-commit` on any
commits you've made (for example, `python contrib/check-commit
273ce12ad8f1` will report some style violations on a very old commit).