Allow tests to be embedded in comments

[ianb]

I've kind of left out the original concept of Python's doctest, where you put tests in your inline code documentation (comments in Javascript, docstrings in Python). It would be nice to have something like that, perhaps, maybe. Mostly it would be just a fancier parser.

[mkllnk]

I was looking for exactly that and really confused when I found your project. The documentation could be improved to point that out. Maybe the name doctestjs is also a bit misleading at the moment. It's more htmltestjs, right?