Added an example showing how to load/save local files
Fixed #111: accept JavaScript objects as input, and turn them into valid JSON
Implemented setting editable/readonly nodes individually via config function `editable`
Improved the `editable` callback: now also provides the path to a node and the nodes value
Oops... uncommented try/catch again
Documented `editable` option
Fixed: shortcut keys to manipulate the nodes are now disabled when mode is `form` or `view`.
Added a documentation page with shortcut keys
Released version 3.1.0
Merge branch 'develop'

Conflicts:
	README.md
Merge remote-tracking branch 'origin/master'