Range
Document that `Range.ToV2` method return `nil` when called on `nil`. Document that `NewRangeFromV2` function return `nil` when called on `nil`. Write corresponding unit tests. Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>
Define Range type in object package. Replace Range in client package with the new one. Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>