Refactoring

Not ready to merge yet, need to load the results of the dependency analysis back into the Makefile (ie. need to add a bunch of `-include` at the end of the Makefile). I'll do that tomorrow.

Next: add more examples to check that the Makefile generation is ok, deal with the release scripts, and start porting my project.
I think we may also want Js and Doc here to hook into `$BROWSER` or some kind of [`reload-browser`](https://github.com/dbuenzli/pkgopkg/blob/master/bin/reload-browser).