The list of tags should be sorted alphabetically. While searching for a tag to add to a post, the list should have **every** tag in it so that you can scroll the **whole** list. While searching for a tag, it should **not** be case sensitive (e.g. if I search with the query "vor" it should show the tag named "Vorlage" - which currently doesn't show up). Additionally the list should contain only tags which have not been added to the post yet.