`network.Address` structure in most cases created once and used read-only.
Replace `AddressFromString` function with `Address.FromString` method with
the same purpose and implementation. Make all libraries to work with value.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
Support processing of NetmapEpoch and NetmapLookupDepth X-headers when
processing object read operations. Placement for operations
Get/Head/GetRange/GetRangeHash/Search is built for the epoch specified in
NetmapEpoch X-header (by default latest). Also the specified operations are
processed until success is achieved for network maps from the past up to
NetmapLookupDepth value. Behavior for default values (zero or missing) left
unchanged.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
