This adds support for the config_cascade when enabling/disabling plugins,
making farming easier.
The changes have been implemented by Piyush Mishra and are a part of the
new extension manager which will follow later. It's the result of a
Google Summer of Code project, the official project page can be found at
http://www.google-melange.com/gsoc/project/google/gsoc2011/piyushmishra/26001

Thanks to Piyush for the work and Google for sponsoring it!

Conflicts:
	inc/lang/en/lang.php