Unify reachableaddresses and IPv6 settings
There's really no difference between "I can't reach IPv6" and "ClientUseIPv6 0". Let's make them redundant. Let's also add an "I can't reach IPv4" option.
See #6027 (moved) and #9067 (moved)
To upload designs, you'll need to enable LFS and have admin enable hashed storage. More information