Purr Data 2.2.0

This release features a cleanup of the sources, an update to the latest nw.js (0.22.1), and a couple of minor bugfixes (please check the git log for details). The build instructions in the README file were also updated.

The original source code repository is maintained by Jonathan Wilkes here. Alternative "JGU" Linux packages built from current Git sources can be found here: Arch, Ubuntu.

Quick introduction to Purr Data: https://agraef.github.io/purr-data-intro