[Feature Request] Multi @ command filter.

I think it would be a neat idea to have a multi @ command filter.

For example my server has a role called Admin and a role called Leader.  If I could use @ commands with a plus symbol to filter to people who contain both of those roles it would be great for exmaple

@Admin+@Leader

This command would only ping people who had both of those roles at the same time and not ping people who were just an admin or just a leader.