Style fixes acording to PEPs
Simplified the second-click-expand and third-click-collapse behaviors, using a couple of local variables and removing the Expansion related code. Also, removed the manual expanded/collapsed indicators, since it doesn't make sense in the second-click expand schema
Introduced the viewport scrolling when the album is not visible to the manual expansion too
Some bugfixes:
* Correctly update the last selected album when using keyboard cursor movement, which allows the entry view to expand when clicking the currently focused album, doesn't matter how it got focused in the first place.
* Fixed some bugs arround rapidly clicking different albums, which caused a incorrectly interpreted double click.