Add gulp-compliant source map support

[RReverser]

pure-cjs returns ready-to-use source map - so why not to add support for it in gulp plugin. Check out how easy it is to implement it at https://github.com/floridoo/gulp-sourcemaps#plugin-developers-only-how-to-add-source-map-support-to-plugins.

[parroit]

Very interesting, I will add support to the plugin

[parroit]

I added support for sourcemap as you suggested, but there is something wrong in generated sourcemap.
I created an example project. For this example, I get this sourcemap:

{"version":3,"sources":["test/example_test.js.map"], ...

I expect sources to contain "test/example_test.js","lib/example.js", nor the sourcemap file itself.
It's not clear to me if pure is generating it wrong or if it is a fault on my side... could you please give me some help on investigating this issue?

[RReverser]

Sorry, was my fault. Please update pure-cjs dependency with npm i pure-cjs@* --save.

[parroit]

Awesome! Now source mapping works well, thanks