admin - bug fix

The way the event delegation was occurring meant that after a save, the
events were being lost.
Event delegation is now being used on the container ($context) which is
WAY better anyway.
admin - fix to plugins

plugins page, on save, didn't go into a 'show loading', which it does
now.
admin - change as a result of earlier bug fix

restoreInputsFromTrackingState was re-applying the tracking, which isn't
necessary any more thanks to event delegation on that apply function.