Fix issue with Chinese input in PowerPoint where finalizing a composition would cause...

Fix issue with Chinese input in PowerPoint where finalizing a composition would cause the slide, shape and edit field to be spoken, rather than just the finalized composition like in all other applications.
Specifically:
	* Add a new focusRedirect property to the base NVDAObject which by default is None. This object should give back an alternative object which should be treeted as the focus if focus ever is given to this original object. This property for now is specifically to fix the PowerPoint issue but in future may be used in other places to replace pointless focus events that bounce all over the place.
	* NVDAObject.objectWithFocus(): Once the NVDAObject has been instanciated, see if this object has a focusRedirect object and if so return that instead.
	* PowerPoint appModule's DocumentWindow NVDAObject: implement focusRedirect to give back the selection object (e.g. an edit field when editing a shape).