Htheatpump

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* updated copyright statements
* some minor improvements in the tests
* fix: removed log of loaded definition file path (``HTHEATPUMP: load parameter definitions ...``)
to get a clean JSON output in the sample scripts (e.g. ``htquery.py``)

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* replaced Travis CI by GitHub Actions
* added async version of console scripts
* updated copyright statements
* some minor cleanup and improvements

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* added new class ``AioHtHeatpump`` for asynchronous communication (async/await) with the heat pump
* Python code reformatting using *Black* and *isort*
* moved protocol related constants and functions to ``protocol.py``
* dropped support for Python 3.5 and 3.6

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* added support for Python 3.8
* some minor cleanup and improvements
* changed log statements to the form with the preferred and well-known ``%s`` (and ``%d``, ``%f``, etc.)
string formatting indicators (due to performance reasons)
* added additional heat pump parameter (data points) ``Hauptschalter`` in ``htparams.csv``

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* changed behaviour of ``HtHeatpump.reconnect()``, which will now also establish a connection if still not connected
* added sample scripts (e.g. ``htcomplparams``, ``htquery``, etc.) to be part of the ``htheatpump`` package
* clean-up of ``setup.py`` and ``MANIFEST.in``

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* added sample file ``htparams-xxxxxx-3_0_20-273.csv`` with a complete list of all heat pump parameters
from a Heliotherm heat pump with SW 3.0.20
* added new sample script ``htcomplparams.py`` to create a complete list of all heat pump parameters
* added some more heat pump parameters (data points) in ``htparams.csv``
* Python code reformatting using *Black*
* changed package requirements structure; some changes in ``setup.py``, ``setup.cfg``, ``tox.ini``, etc.