Shelephant

What's Changed
* shelephant_dump: adding `--keep` option by tdegeus in https://github.com/tdegeus/shelephant/pull/101


**Full Changelog**: https://github.com/tdegeus/shelephant/compare/v0.18.0...v0.19.0

API changes
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* Making rsync default to check difference (removes ``--check-rsync`` option).
To get the old default use ``--check-manual``.

* ``shelephant.rsync``: removing ``tempfilename`` and ``force`` options.
The temporary file is now internal, with the proper clean-up.

* ``shelephant.rsync``: removing ``rsync`` option. Use ``rsync_path`` instead.

* ``shelephant_dump``: adding ``--cwd`` option.

* rsync: interpreting cryptic both in send and receive mode
* [CI] Minor style update

* Fixing bug in command-line parsing of ``shelephant_send``: defaults were not selected.

Fixing typos

* Normalising paths in copy functions