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feat(opts): underlay sock opt type

fix(ci): go 1.18

fix: go mod download

fix: go mod tidy

fix: there is no uint8 sockopts really

feat: generic sock opts

fix: rename buff -> data

fix: unix.SocketConn.Set*Deadline() not returns cancel function to ensure it has been locked again

feat: ListenPacket handler now can return errors

feat: receive sockaddrs

fix: remove unused channel allocation for dispatcher

feat: unixx.SocketConn, cmsgs

fix: set setsockopt values in constructors

feat(test): check that RTT > 0