Only extract links

[hoijui]

With a command line switch, like --only-extract-links, only that first phase of the process would be done, and the list of links would be printed.

This can be useful for debugging, for using other tools for doing the other steps, gathering statistics about links or the changing of links over time, or .. who knows what!
It would move mlc closer to the UNIX style of software, and give more power to the users of this software.