alpha of major release Version 3.0a

This release is the first alpha release of the new version 3.0. Please
be aware that the API will still change until v3.0 is released.

changes
^^^^^^^
- change the project's license to MIT in accordance with the contributors (see python-escpos#171)
- feature: add "capabilities" which are shared with escpos-php, capabilities are stored in
  `escpos-printer-db <https://github.com/receipt-print-hq/escpos-printer-db>`_
- feature: the driver tries now to guess the appropriate codepage and sets it automatically (called "magic encode")
- as an alternative you can force the codepage with the old API
- updated and improved documentation
- changed constructor of main class due to introduction of capablities
- changed interface of method `blocktext`, changed behavior of multiple methods, for details refer to the documentation
  on `python-escpos.readthedocs.io <https://python-escpos.readthedocs.io>`_
- add support for custom cash drawer sequence
- enforce flake8 on the src-files, test py36 and py37 on travis

contributors
^^^^^^^^^^^^
- Michael Billington
- Michael Elsdörfer
- Patrick Kanzler (with code by Frédéric Van der Essen)
- Asuki Kono
- Benito López
- Curtis // mashedkeyboard
- Thijs Triemstra
- ysuolmai

minor release v2.2.0

changes
^^^^^^^
- fix improper API-use in qrcode()
- change setup.py shebang to make it compatible with virtualenvs.
- add constants for sheet mode and colors
- support changing the linespacing

contributors
^^^^^^^^^^^^
- Michael Elsdörfer
- Patrick Kanzler

bugfix release v2.1.3

changes
^^^^^^^
- configure readthedocs and travis
- update doc with hint on image preprocessing
- add fix for printing large images (by splitting them into multiple images)

contributors
^^^^^^^^^^^^
- Patrick Kanzler

bugfix release v2.1.2

changes:
- fix File-printer: flush after every call of _raw()
- fix lists in documentation
- fix CODE128: by adding the control character to the barcode-selection-sequence the barcode became unusable

contributors:
- Patrick Kanzler

bugfix release v2.1.1

changes
^^^^^^^
- rename variable interface in USB-class to timeout
- add support for hypothesis and move pypy3 to the allowed failures (pypy3 is not supported by hypothesis)

contributors
^^^^^^^^^^^^
- Patrick Kanzler
- Renato Lorenzi

release version 2.1.0

changes
 * packaging: configured the coverage-analysis codecov.io
 * GitHub: improved issues-template
 * documentation: add troubleshooting tip to network-interface
 * the module, cli and documentation is now aware of the version of python-escpos
 * the cli does now support basic tabcompletion

contributors
 * Patrick Kanzler

Release version 2.0.0

released version 1.0.9

Updated README and documentation

Updated project version