toggler & inputextender: Replaced "animationstep" events with "animation" event

This is done by using jQuery.fn.animateWithEvent. Should give a little performance boost during
animation executions since only one event will be triggered and bubble up the DOM per animation
(before, an "animationstep" event got fired for each animation step and on completion, though
using different parameters depending on the occasion).
- Allow for greater flexibility when using the event, extensions such as widgets can now hook into
  all animation stages.
- Resolved the ugliness of jQuery.ui.toggler specific handling in jQuery.ui.inputextender.
- Introduces another new event for inputextender, "contentanimation" which fires on the widget in
  case the new "contentAnimationEvents" option is specified with the name of an event triggered
  on the inputexter's extension node.
Requires change I503ee1b009bec200558c16f15a558e02d5757741 for the Selenium tests to run
properly.

Change-Id: If57ee1eea13d1d016915b8e06b8e9cea05c63b5e