quip: Quips cannot be deleted

[aperezdc]

It is possible to use bot: quip <text>, and the bot will reply with the index of the newly added quip, but it is not possible to delete them.

Proposed interface:

• [x] quip add <text>
• [x] quip del <number>
• [x] quip get <number>
• [x] quip get — Obtains a random quip
• [x] quip <number> ­— Same as quip get <number>
• [x] quip — Same as quip get

[aperezdc]

Idea: it would be nice as well to provide a way of obtaining a quip given its index. I have updated the description with the proposed interface.