Filter subreddits from /r/all

So this is a bit larger of a change, so if you don't like some of my implementation just let me know what your concerns are and I'll make the necessary adjustments and re-commit. Basically with this feature, you can hide subreddits from the context menu on any post (hides the subreddit they belong to). This hides the posts  when viewing /r/all but not any other view. The list of subreddits is a CSV that is in the behaviors tab of the preferences (under the post subheading).