Added support for draggable error and complete marbles.
Added those marbles to 'merge' as an example.
Adding those to the rest of examples should be part of following tasks ("Add examples related to errors", "Interactively add/remove marbles from an InputStream" in TODO).
Added support for draggable error and complete marbles. Added those marbles to 'merge' as an example. Adding those to the rest of examples should be part of following tasks ("Add examples related to errors", "Interactively add/remove marbles from an InputStream" in TODO).