Delete ratelimit messages shortly after sending

[clubby789]

Ratelimiting commands helps reduce spam, but still spams a little, i.e.

@username, You may not use the ping command again for another 7.9 seconds.
@username, You may not use the ping command again for another 7.6 seconds.
@username, You may not use the ping command again for another 7.3 seconds.
@username, You may not use the ping command again for another 7.1 seconds.

Deleting these ratelimit messages a few seconds after sending them would reduce this.

[diogoscf]

Good idea. Will do once I get back

[diogoscf]

Done in 656637374fd20772a14e25228993309e588d53f2