More cleanup

Couple more (hopefully) useful additions.

* Added .editorconfig. Provides a way of defining common editor/whitespace settings for files in a project, avoids messy tab/space/trailing-whitespace issues. Good idea to install and editorconfig plugin, e..g https://github.com/sindresorhus/editorconfig-sublime
* Moved history out into more standard CHANGELOG.md
* Moved jshint settings into .jshintrc, makes it easier to run directly