[GUI] Show user's playlists and allow to download them.

[exislow]

I have basically created a view on the left side of the GUI, that shows the user's playlists. You can click on them and the tracks will be displayed in the search result table.

It is now possible to select several tracks and click on download, to download them without the need to click "Download" for every single track.

According to your coding style, you are likely a C# engineer. I tried to create a more Pythonic code, thus it differs from your style a little bit. Your code is a little bit hacky and not very Pythonic. Extending it makes it hard but it works stable this way. There is a lot of refactoring potential.

But anyway, I would be glad, if you could merge this pull request and push it to PyPi.

[chiefbud]

Would this allow users to keep the artist>album formatting? Or would this create a playlist folder similar to it's current behavior when searching via a playlist?

[exislow]

The formatting and download behaviour is still the same! Tracks getting downloaded in artist > album! But I will maybe try to implement an option to choose between this an playlist > track.

Would be glad if you could merge this PR. And thank you for your work. I love this project!

[exislow]

@yaronzz & @chiefbud: Is it possible to get this merged?

[chiefbud]

Well done 🌟