Added generic LoadObject methods that can load any classtype from a

Added generic LoadObject methods that can load any classtype from a
resources and return it as a wxObject (Assuming there is a handler for
it.)

Enabled wxFrames and wxDialogs to be loaded using a new instance
rather than only with existing instances.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@16720 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775