[collectd] [PATCH V2] add Modbus/RTU support to modbus plugin

[Marc Fournier]

Excerpts from Eric Sandeen's message of 2014-12-10 22:38:09 +0100:
> This allows access to a local RS-485 serial port
> via the modbus plugin
> [...]

Fabien Wernli was kind enough to test your patch on his modbus equipment
to make sure there was no side effect on the existing modbus-over-TCP
functionnality. So I'm pleased to inform you your patch has been
included and will be part of upcoming 5.5 release.

Thanks a lot Eric !

Marc