Displaying scenarios that use an undefined step

[stof]

Currently, Behat displays the code to create undefined steps (which is very cool) but it does not say in which scenerio they are used (forcing us to read the entire output to find it, and even worse for the progress formatter as it does not display the name at all). Adding the scenario using them would be a great add-on, especially when the undefined step is in fact a typo in a feature file.