Rewritten as a Gem, with more standard Ruby syntax

I've been using your API for an experiment with BeeLine Reader (https://beelinereader.com) and wanted to contribute back some syntactic improvements to the Ruby library.

* It's now a gem (unreleased).
* Everything is rooted in the new `Pearson` module.
* Moved the monkey-patching of Hash to a method.
* Used underscores instead of CamelCase for methods and variables.
* Fixed a few typos and spelling issues.

Feel free to edit as you see fit.