Incremental Update Implementation (cleaner)

[adnsistemas]

What?

Ability to make incremental updates to PDFs

Why?

Required for proper electronic signing of documents.

How?

Making an snapshot of the original PDF and marking changed Refs that need to be saved in the "increment"

Testing?

All tests and Node app.

New Dependencies?

No

Screenshots

N/A

Suggested Reading?

Yes

Anything Else?

Had to make a couple of small changes to package.json in order to be able to build, test, and commit the changes.

Checklist

• I read CONTRIBUTING.md.
• I read MAINTAINERSHIP.md#pull-requests.
• I added/updated unit tests for my changes.
• I added/updated integration tests for my changes.
• I ran the integration tests.
• I tested my changes in Node, Deno, and the browser.
• I viewed documents produced with my changes in Adobe Acrobat, Foxit Reader, Firefox, and Chrome.
• I added/updated doc comments for any new/modified public APIs.
• My changes work for both new and existing PDF files.
• I ran the linter on my changes.