copy filter: async function and/or function called with fs.stat result

[thomas-riccardi]

It would be great to have a filter-like option on copy where the function would be async (with a callback) (useful for fs.stat(item)).

And/or have a filter-like option where the function is called not with a string path, but with the result of fs.stat on it (in addition to the path of course). (This could still be useful even if async filter function is implemented, because it would avoid double call to fs.stat).

Currently since we have neither feature, it's not possible to filter by path type (for example: I want to keep dirs called 'bla', but not files called 'bla').

[jprichardson]

That makes sense. I'd like something like that too. Eventually, I'm going to rewrite copy on top of https://github.com/jprichardson/node-klaw. This would enable such behavior. This will be awhile before this happens. My priority is to get this module to 1.0. Closing and tagging as future.

[RyanZim]

Filter function has been added, stat is under consideration in #220