change uses of get() and set() to use accessors
popup.js: require dui/themes/load!common to get duiPopup class
Fix _Widget-attr test to work w/direct accessors.

Removed tests for automatic mapping of attributes, since that's no longer supported.   Also
removed tests for features that are covered by the tests for Stateful, and moved a few tests
to tests/Stateful.js

Finally, stopped using _TemplatedMixin in the tests since I'm going to remove it.
Remove _AttachMixin, _TemplatedMixin, and _WidgetsInTemplateMixin.
They are essentially replaced by the handlebars plugin.
get _HasDropDown working again after ES5 accessors check in
remove deprecated code etc. from helpers.js
Stateful: fix comment
Use register() for declaring widgets and declare() for base classes.
Updated register() to search inherited properties too for shorthand notations
like _setFooAttr: "focusNode".
Switch from dojo.declare() to dcl.
No auto-chaining yet.
automatic chaining for postMixInProperties(), postCreate(), startup(), and destroy()