diff: improved handling of Git diffs with " quoting Kallithea would intentionally and explicitly fail with an ugly exception when trying to parse Git diffs with quoted filenames. Improve this by parsing quotes ... and ignore them, as long as they are matching. The content inside the quotes might be \-escaped ... but that could potentially also be the case without quoting. We will fix that later. Adding some test cases that before would have failed to parse and raised an exception. Thanks to stypr of Flatt Security for raising this.

# requirements.txt file for use as "pip install -r requirements.txt" as a
# readthedocs compatible alternative to "pip install -e ." which is a working
# alternative to "setup.py develop" which doesn't work with Mercurial 3.7
.