Allow users to exclude tags in the search

[Shiroizu]

(Suggestion from the google form survey)

For example, to filter out songs with the epilepsy warning -tag.

[riipah]

Could be useful regarding #150 as well.

Does it matter if this is a global user setting (for all searches by that user), or per search (added every time)?

[riipah]

mentioned

[lalondeguy]

I've been thinking this as well, and I would've opened an issue about it if you hadn't already. I've also been thinking about if it would be possible to exclude artists from song/album searches? (For example, say you wanted to search the insane fantasy or denki drug tags and exclude anything by Kikuo, or if you wanted to additionally exclude Kanaria from searches of the unsupported language tag that you've also excluded the English tag from.)