Filter out low-quality items#2

Some feeds like HN or Reddit are very noisy and have lots of low quality content, in addition to high-quality items. Scour should identify the higher quality items and either hide or down-rank the lower-quality ones.

@Moon I’ve added a model that assesses content quality and am now filtering out content that it thinks is low quality. I’m curious if you still see things that seem low quality or notice a difference.

I’m going to mark this as completed for now but I might do another iteration on it in the future if people notice too much low-quality content appearing in their feeds.