Changes between 5.5.3 and 5.6.0

This is a minor release with 2 new features and 2 bug fixes. All users of the 5.x.x series are encouraged to upgrade to this version.

Introduce Connection#openChannel that returns an optional

GitHub issue: #431

Add option to make RpcClient fail early if there are no bindings

GitHub issue: #417

RpcServer doesn't stop when its thread is interrupted

GitHub issue: #428

Make properties private in JSON RPC classes

GitHub issue: #417