Sort by recently interacted with

[lemon24]

It would be nice to get entries the user recently interacted with.

"Interacted" means, at a minimum, marked as (un)read/important. "Set tag" might be nice. "Downloaded enclosure" might be nice too.

Arguably, the mark_as_read plugin (and plugins in general) should not count as an interaction. If we use read_/important_modified, mark_as_read should probably set them to None – but this would likely break the "don't care" tri-state (#254 (comment)).