Extension:E3 Experiments

The E3 Experiments extension was previously deployed as a scaffold for members of the Editor engagement experiments team to use when deploying simple experiments.

Installation
At one point you also needed to install:
 * Extension:EventLogging which logs the acceptance and completion of open tasks.
 * Extension:PostEdit which indicates when a user is viewing a page after successfully editing it (now moved to core, ).
 * Extension:ClickTracking for Account creation user experience experiment (which in turn requires Extension:UserDailyContribs)
 * Extension:Vector which provides the "Exclude me from feature experiments" user preference under "Appearance"