Allow Moderators to mark deleted text with flags (such as SPOILER for game spoilers, or TOS for issues which may require suspension/banning now/later)

Some broadcasters want to verify why people were moderated, and they don't want to risk reading deleted/purged chat messages only to come across a current game spoiler they were trying to avoid.

When moderators delete the text of a user, if they could later click on it in the message history and flag it with <SPOILER></SPOILER> or <TOS></TOS> it would be great.