Dms-tools2

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* added `compareprefs` module

* added `rplot` module to enable plotting with `ggseqlogo <https://omarwagih.github.io/ggseqlogo/>`_

* Added `omega` overlay option to ``dms2_logoplot``

* Fix bug with ``dms2_logoplot`` when using wildtype sequence overlays

* Fix bug with ``--fracsurvivemax 0`` to ``dms2_logoplot``

* Scale pseudocounts when using ``dms2_prefs`` with ``--method ratio``, which should give more accurate values when depths differ across samples.

* Some minor bug fixes.

* Fix bug with handling of disulfide-bonded cysteines in ``dssp`` output.

* Added `colors` option to `plot.plotCorrMatrix`

* Added ``--diffprefs`` option to ``dms2_logoplot``

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* Added programs and docs for `fracsurvive`.

* Added ``--scalebar`` to ``dms2_logoplot``.

* Add `grouplabel` option and preserve group order for faceted plots by batch programs.

* Handle dependencies without `__version__` attribute

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* Added ``--sitemask`` option to ``dms2_bcsubamp`` / ``dms2_batch_bcsubamp``.

* Standardized color scheme in ``*_cumulmutcounts.pdf`` plot.

* Ensure naturally sorted average prefs from ``dms2_batch_prefs``.

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* A few packaging changes for PyPI

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This version is a complete re-write of `dms_tools <https://github.com/jbloomlab/dms_tools>`_ version 1.2.2.