A couple of big changes here. A lot of logic moved to graph.php.

The PHP plugin files have been rewritten to JSON. In these JSON files
*everything* is optional. Also *NOT* having a JSON plugin file won't
block you from having a graph. The JSON will just make the graphs
prettier (by having a title, y-axis title, legend, colors, etc..).

The Collectd types.db file is parsed and used to determine RRD content.
When things are not defined in the JSON it will fallback to a default.