[focus-next-unread-user-or-channel] - Ignore muted channels

[eyenx]

Hi

It would be very cool to have an additional keybinding focusing to the next unread user or channel but ignoring muted channels.

The idea behind it is: I got around 50 open channels, and want to not switch automatically to the muted channel if it has new messages, I muted it for a reason.

I could help implementing this if it is appreciated.