Massive update

* widget.combine (appendTo, prependTo, replaceIn) returns now also the
list of rendered widgets instead just the rendered containers.
* underscore.js is now a requirement
* The widget.js now supports a global after-render function (addEvent,
removeEvent)
* The widget now have a function to get configured from outside by
calling config(obj). This will invoke the onConfigChange callback
* The widget#combine now returns the widgets in the order as they were
passed in
* Reduced the timeout of a widget to get faster responses