#4 Hide channel mode changes from non-OPs

[Jerry Horn]

I've been getting requests from channel ops and opers to
hide certain mode changes from non-ops and non-opers.

Currently, any user in a channel can see mode changes.
The main ones we'd like to hide are +b and +f.

Perhaps this could be made as a server config setting?

set::hidechanmodes::modes
or
set::showchanmodes::modes (similar to oper-only /stats)

This would help bans be more effective, if we only ban a
nickname instead of a hostmask (such as for AOL users).