Updating Rollup version with changed api + package-lock

[Mazrog]

I updated rollup to latest version I found at this time, and made some changes in the process function due to api changes. Also some esthetics changes, with const and arrow functions.

In details: bundle.generate produces an object with an output property containing an array of chunks.

Unfortunately, I am not the best user of mocha testing, I tried to update it a bit, but did not went out well :( If anyone wants to fix it, it would be with pleasure !