Prevent pings by the bot (most importantly @everyone)

[Olexorus]

Previously it was possible to use @everyone and @here even when the bot didn't have permissions for this (I assume that's because it's using a webhook?). This can be really problematic, if someone abuses it, it is hugely annoying to everyone on the server, and I don't think you can really do anything about it as a server admin.

[Reimnop]

Looks good to me! Thank you for the contribution!