add multiple quotes (replying to more than one comment at at a time)

[plebe1us]

We are changing the UX to be specific to the client, so 5chan boards will be intended to be used on 5chan only (and not other protocol clients like Seedit), so we can add multiple quotes as a feature specific to 5chan.

The user should be able to quote multiple replies like they do on 4chan.

• while replying to a reply, clicking a different CID should automatically paste the CID in the content as quote.
• all quote CIDs should render the relative comment when being hovered.
• all quote CIDs should render the relative backlinks in the replies they refer to.
• also, re-enable quoting OP by clicking the thread's CID in the OP card.

[plebe1us]

requires #658