Update qtAttributePreview
Desired updates:
- Initialize Qt connections to duplicate the logic in
pqSMTKCallObserversOnMainThreadBehavior::forceObserversToBeCalledOnMainThread()
. - Set the initial dialog size to 640x480 (width x height)
- Support both attribute template file (.sbt) and resource file (.smtk) input.
Edited by John Tourtellott