Pymcws

* Added sensible default behaviour to library.playlist() and files.search(). Both will now return lists of MediaFiles by default.

* Upgraded to Python 3.9 and improved type hinting.
* Added files.playback() to retrieve current playlist from zones based on https://github.com/kenomaerz/pymcws/issues/7.
* Added library.create_fields() to create new fields. However, MCWS currently fails to execute the request, see https://yabb.jriver.com/interact/index.php/topic,131470.0.html

* Major rewrite of pymcws that fixes everything I started to dislike about the structure.
* Usage is more intuitive now, see Readme.md and example.py for details.
* Editing and saving files is now possible.
* Several additional endpoints implemented.
* Finally added tests. Please read the documentation carefully if you intend to run them. They can destroy your library.

* Implemented playback_loadDSPPreset based on https://github.com/kenomaerz/pymcws/issues/6.

* Introduced session management for established media servers.

* Added automatic field resolution. Fields are automatically converted to and from their corresponding python types by the API, sparing you the postprocessing.
* Because of this, the required version of MC is now 26. Earlier version support is possible but needs to be requested.
* Play recipes use more reasonable defaults for shuffle and repeat.
* Several smaller bugfixes.