Fix for Python 3.x in replace_more_comments()

There was a bug that made replace_more_comments() unusable for Python 3.x. In the _extract_more_comments() function a heap requires the ability to make a comparison. You did add the __cmp__ function to the MoreComments() class, but unfortunately cmp() has been gotten rid of in Python 3 and been replaced by __lt__. Anyway, there it is. You will probably understand it more if you just look at the code, I'm bad at explaining stuff. Anyway, enjoy!