Merge with newer code from nowplaypadgen project

[paraenggu]

radiorabe/nowplaypadgen provides modern replacements for the Show, Track and TimePeriod objects (including tests and docs). Those could be integrated and replace the current objects.

• Show
• Track
• TimePeriod
• Tests

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• [dlplus] Use jinja for templating strings nowplaypadgen#20
• uid vs uuid in Show nowplaypadgen#15
• feat: use Show from nowplaypadgen project #132

[hairmare]

From what I've seen some of the linked modules seem to cover a more narrow use case than what we are currently doing in nowplaying.

IMO there is still some refactoring to be done to make this replacement possible. Mainly the input parts are what still needs some work as those don't have much test coverage yet.
I'm also not quite sure on how we would proceed on the nowplaypadgen side of things. Do we want it to stay viable as a standalone module in it's own right. I certainly think it might be of interest to a larger audience if it stays standalone.

We also need to consider how we would like to handle our core python object models going forward. I've been considering a solution based on something like a rabe.commons python module that is primarily there to contain some very simple and abstract base modules but that is most certainly overkill.