OpENer v2.2.0 - CT-15 ready

Hi all,

again, after almost one full year, I present a new release of OpENer. Why now? First, I achieved that OpENer can pass CT-15 recently, and also I was again able to attend ODVA's PlugFest, where a lot of additional testing is performed in addition to the CT tool. Again PlugFest was quite successfull, with OpENer passing the probably hardest test for Adapter devices, the Common and Adapter tests. Therefore I decided it is time for a new official version of OpENer.

In this new release updates OpENer to implement ODVA's April 2018 CIP and EtherNet/IP specification, enabling to create product, which are able to pass CT-15 and PlugFest tests.
In addition a MinGW port was provided @jkvatne (thanks for that!), POSIX got a modification to enable RT features if a full preemptive Kernel is available.

In order to further enhance code quality, additional static code checking is now performed via SonarCloud, in addition to the tests via CppUTest, Travis CI, and Coverity Scan.

Also several bugs were fixed, over the year and especially via PlugFest testing, also with the help of the community, which reported several bugs and also provided some bug fixes for OpENer.

I hope you find the new OpENer version useful. Please keep reporting errors and bugs!

Best regards,
Martin