Convert to MultiFilter

[chriseppstein]

I've got a fork of Broccoli Filter with correct support for multiple output files even with caching. I've updated the filter branch (rebased on master to get all the latest work) and made it use the new MultiFilter class.

For reasons of personal expediency, I've published this as a fork, but if you like it, I will re-work it so that it is mergeable.

Note that beyond just sourcemaps support, generic one-to-many output is ideal for other use cases. In particular, I'm looking to support a postcss plugin of mine that generates multiple output files from a single input file by extracting :lang pseudo selectors to a lang-specific file.

Note that I'm also trying to get the Filter changes merged in so that the official Filter class has support for this. broccolijs/broccoli-filter#38

[jeffjewiss]

Hey Chris, sorry for the delay in taking a look at this.

These changes look great and seem like a step up from the filter branch I had started. Thanks for submitting the change! I'd be happy to get this merged in and published as V3 of the plugin.

Do you mind reverting the readme and package.json changes for the fork? I think other than that, the only thing that stood out to me in the PR is the version broccoli-multi-filter was published under (1.2.3-multi.1). Would it make sense to publish this as 2.0 since broccoli-multi-filter is a separate module on NPM, which you own?

Let me know if it would help for me to leave comments on the files changed.

Also, are you interested in being added as a collaborator on the repo and package?

[jeffjewiss]

Hey Chris, I haven't heard from you in a while, so I'm going to close this as I decided to merge the existing filter branch into master. Let me know if you'd like to pick up the discussion where we left off.