Pure JSON code

[BigBlueHat]

JSON5 is cool for what it is, but not sure it's a mandatory requirement for this package--and having it "in the way" was meaning lots of build overhead to use kle-serial in a browser.

Consequently, these two commits...

1. Remove JSON5 as a dependency.
2. Remove the .parse() method altogether as it can (should?) be done at an application layer if/when needed (+/- JSON5 support if that's wanted).

This then focuses this library on just deserialization. Huzzah! 😀

Thanks for building this and KLE! 🎩