Segno

* Fixed [95](https://github.com/heuer/segno/issues/95):
``helpers.make_wifi`` and ``helpers.make_wifi_data`` may return
invalid data if any input contains characters which can be
interpreted as an integer.
* Updated ``helpers.make_wifi`` and ``helpers.make_wifi_data``
signature and doc strings to match the stub / type hints.

Fixed: Stub files (type hints) were missing from the source distribution.

* Fixed 84
CLI ``--encoding`` was used for the encoding of SVG documents and not
for the encoding of the QR code.
Added ``--svgencoding`` to specify the encoding of SVG documents.

* Improved API docs
* Added support for type hints for the public API (stub files)

* Added `QRCode.svg_inline` method which returns a string which can be used to embed the SVG directly in HTML pages.
* Improved documentation <https://segno.readthedocs.org/>
* Improved code quality
* Switched from tox to nox
* Utilize flake8
* Moved metadata from setup.py to setup.cfg