3.1.2 release

[Adam Crain]

Emile put in a lot of time the last 2 weeks, and we have released 3.1.2:

https://github.com/dnp3/opendnp3/releases/tag/3.1.2

This release fixes all outstanding issues that we're aware of (seriously, look at the issue tracker).

It's my hope that this will be the last release of OpenDNP3.  We're preparing to release a 1.0.0 of our Rust library (which now has C++ bindings), and this will lead to an end-of-life date being announced for OpenDNP3 soon.

I'll post again in the next couple of weeks to provide more details on what this EOL means.

Please look through the Changelog and test the fixes for any issues that you've been waiting on.

Regards,

Adam