NetworkInfo
Document that `NetworkInfo.ToV2` method return `nil` when called on `nil`. Document that `NewNetworkInfoFromV2` function return `nil` when called on `nil`. Write corresponding unit tests. Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>
Define NetworkInfo structure. Implement constructors, fields getters and setters, binary and JSON encoding methods. Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>