Allow test reports to access test context

To build some custom reports we need to access the test context during test reporting.
We added testContext as parameter to the methods of TestActionListener before we found https://github.com/christophd/citrus/pull/32.
However the outlined solution
("You can now access the test context on the test case object. As the test case is accessible in the action listeners you can get the test context there, too. I think this is less intrusive regarding API stability.") did not work for us.
How can we access the test context from test case?

Start by tracing the TestActionListener methods and the test case object referenced in the issue, then verify how the test context is exposed during reporting. Reproduce the reported failure with a custom report and determine a supported way for listeners to access the context; done means the access works without the proposed API change.

Written by the indexing model from the issue text.