Release 3.0.1

Fixes

• fix mdf3 _prepare_record in case of channels with addition byte offset
• fix algebraic conversion
• improve string channel handling
• fix csv export
• fix appending groups with no samples
• fix cut method when the interval is not found in the measurement
• fix for get method in case of channel with no samples
• fix mdf version3 byte array
• fix mdf version 3 saving of groups without samples with options "minimum" and "low"
• added "physical" method to Signal class
• fix handling of LE strings
• fix appending of CANopen types
• fix handling of channel arrays