Delete messages by increasing date for a more dramatic effect (or more discretion)

[Raphael-Boichot]

I've just deleted 32k messages from a given Discord and I had some messages to send before leaving. As Undiscord sometimes crashes (due to Discord), I had to relaunch it several times during the process that lasted for 2 days. As my last messages were deleted in priority, it was obvious I was using a delete bot while talking to people, with the risk of being banned before the end of deletion. So my idea: allow a chronological deletion but older messages first, for a more sneaky action.

[Raphael-Boichot]

And sorry, same as:
#515