Allow newFilename to be returned from hook();

[jimthedev]

At the moment this line https://github.com/ariporad/pirates/blob/master/src/index.js#L76 allows you to change code but it does not let you return both newCode and a newFilename. Pirates should allow authors to return either an object that has newCode and/or newFilename properties. If a newFilename is returned then the hook would use that when calling compile.

Would you accept a PR for this @danez @ariporad? Thanks!

[danez]

That should be fine to implement as long as we do not break backwards compatibility. Out of interest, what is your usecase?