User feedback

[eartharoid]

Replace the surveys feature with a per-category-toggleable feedback feature.

If the ticket creator closes the ticket, show a modal with a short text (1 character, 1-5 rating) input field (later to be replaced by a select menu) and a long text (comments) field, both optional.

If staff close the ticket, wait a while before deleting the channel for the user to click the feedback button (if the user is still in the server).