Don't give up on linking just because some files already exist

[ro6]

I often end up running dploy into a directory where some subset of the files I'm linking to already exist. I'm glad I get warnings about that, and that it doesn't clobber the files, but I would prefer if it still went ahead and linked any files where there wasn't a conflict. If this behavior doesn't work for others' use cases as the default behavior, it could be hidden behind a flag.

[arecarn]

I could see how that might be useful. I'll see about adding that when I get some time.