jaconv is available for more Python-versions and seems to be more
professional. Apart from that I added jaconv to the test-requirements
but not the requirements. (If the katakana-stuff really works we can
later add it as a real dependency)
This code is adapted from the works by Frédéric Van der Essen in
pyxmlescpos.
I had to adapt the code completely in order to make it compatible with
modern unicode-handling
Further changes:
* improve text unittests in CLI and MagicEncode with hypothesis
* add feature force_encoding in order to enable old behaviour
* disable cli_text_test (for now)
* fix charcode(): it does now cooperate with the new structure
* remove redundant variable codepage from class Escpos
Patrick Kanzler