v3.0.1

A dot zero isn't a dot zero without few problems, so I've released to fix problems with non-recent Linux kernels and other platforms.

• Avoid useless serial_mode integer when TIOCSRS485 isn't supported
• Fix compilation failure on Windows (RS485 support) by Tobias Doerffel
• Properly check TIOCSRS485 define by Matthijs Kool
• Rename package to libmodbus5 to fix lintian warning.