target.getEvent() no longer looks for smart events

The complication of smart events needing the signature passed to them made the
target.getEvent() signature really counterintuitive. And I wanted
target.getEvent(type, publishedOnly), which would make it worse if the sig
also needed to support passing smart method ('subscribe', 'fire', etc) and the
calling args.
DOMEvent tolerates el.nodeType || el === window

Needed for DOM event subscriptions against the window object
(e.g. window.onload)
Remove augment(Node, ET) in favor of extend()

The YUI implementation I have been shimming this into now has Node extending
EventTarget rather than beign augmented with it. As such, Node's overridden
version of detachAll and purge can be declared directly on the prototype.
Now working. Yay tests.
s/eventx/eventx-base/ in use()