v0.7.1

Added

• Zeroize memory held by PrivateKey when dropped.
• Add methods ua::DataValue::with_source_timestamp(), ua::DataValue::with_server_timestamp(), ua::DataValue::with_source_picoseconds(), ua::DataValue::with_server_picoseconds().

Changed

• Rename methods ua::DataValue::status_code() to status(), ua::DataValue::with_status_code() to with_status(). Deprecate the former methods.