Byml

Fix --version not working for the YML to BYML conversion driver.

* Added preliminary support for byml v4.
* Added a note to the readme about the hard dependency on PyYAML's C modules.

Bug fix: use UTF-8 explicitly to avoid output issues on systems that don't default to UTF-8 (notably Windows).

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Compatible with pypi. This can now be installed with just `pip install byml`.

Note that [wszst](https://szs.wiimm.de/wszst/) is still required for the CLI scripts if you intend to modify yaz0-compressed files.

Compatible with pypi. This can now be installed with just `pip install byml`.

Note that [wszst](https://szs.wiimm.de/wszst/) is still required for the CLI scripts if you intend to modify yaz0-compressed files.