add !qotd commands

[weslayer]

admins manage a question queue via s!qotd subcommands, and the bot automatically posts the next question to a configured channel every day at 8am.

questions should be stored in SQLite and move to a "past questions" table once posted

things that need to be added:

• s!qotd add <question> -- append a question to the back of the queue
• s!qotd priority <question> -- add a question to the front of the queue
• s!qotd remove <id> -- remove a question by ID
• s!qotd list -- view the current queue
• s!qotd past -- view previously posted questions
• cron job that removes the first question from the queue and adds it to the past questions table

s!qotd list
> [Embed: "QOTD Queue (3 questions)"]
>  #1 (ID 4) — What's your favorite IDE?
>  #2 (ID 5) — Tabs or spaces?
>  #3 (ID 6) — What got you into CS?

s!qotd past
> [Embed: "Past QOTDs"]
>  03/14 — what's your favorite language? (added by cindy)
>  03/13 — Vim or Emacs? (added by cindy)

MAKE SURE NOT TO USE THIS COMMAND IN BOT-COMMANDS CHANNEL THEN IT WOULD NOT BE GOOD