Update for MQ V9.1.2

This release works with the v4.0.1 release of the mq-golang repository, so has been given the same tag.

It includes updates for MQV9.1.2 compatibility and various bug fixes/enhancements.

Create a version

This is the first tagged version for the repository, to make it easier to select specific versions in future. The version is set to be the same as the corresponding mq-golang prereq packages (in the vendor tree here)