Allow the client to sync multiple directories

[stephenh]

Right now I invoke mirror client three times, once per directory I want to sync. The mirror server can handle multiple directories, the client should be able to as well.

[nathantsoi]

I have the same issue. I was wondering if this was the correct way to run the client or if there are performance implications for running it thrice?

No worries if this is the right way to do this!

Also, great work @stephenh, mirror is fantastic!

[stephenh]

Great, glad you're liking it!

And yep, just running it 3 at a time is fine/what I do. Probably a little wasteful, but I haven't noticed anything that's more annoying than "oh right, I have to run it three times". :-)

Behind the scenes mirror also uses facebook's watchman, which ends up being a single daemon to serve all watchman-driven tools on a box, so it can dedup/manage file watchers as necessary/if needed.