Allow for commenting of steps

[janschaefer]

It is already possible to provide an extended description to steps by using the @ExtendedDescription annotation. However, sometimes you want to comment a certain step-invocation and not all invocations of that step. This comment should also appear in the report.

Example:

given().something();
when().some_step()
  .and().some_surprising_step()
   .comment("a comment is especially important here because the step surprises the reader")
  then().something();

[Airblader]

Just to clarify, this should be really a new piece of information on a step rather than just setting the extendedDescription of a particular step instance?

[Airblader]

Also, from my understanding of the codebase, this would roughly involve the following:

• Add a new comment property to StepModel.java, similar to the extended description, and add it to the JSON protocol.
• Introduce a new comment method in StageBase.java (or Stage.java to make it language-aware).
  • Introduce a new annotation for such a method, similar to @IntroWord.
  • Handle this annotation in ScenarioModelBuilder#stepMethodInvoked by setting the comment property of currentStep to the argument of the called method
  • TODO: can we somehow enforce that such a comment method must have exactly one argument of type String? That would be nicer then throwing a runtime wrong usage exception.
• Handle the comment property in the HTML reporter (and possibly others?)
  • TODO: how should it be displayed?

I hope I got the basic design of this feature right.