Filter recipies by subscribed feeds

[m42e]

Filter or sort recipies by the subscribed feeds.

[teroshan]

Doesn't look that hard, I guess we should modify RecipeManager.php to add this.
A list of RSS feeds urls should be queried from ttrss' database, matched against the url of each recipe so the filtering can be done.

Sorting the recipies would be one way of doing this, but filtering out the recipes seems easier and better for me.