Add functions for extracting wxStrings that allow the user to specify the default fallback string, or to use the key as the default fallback string.
Add convenience functions for extractings resources and strings from a ResourceBundle using a series of keys.
Use AUI to manage the layout of the trace viewer frame. Move the ExplanationViewer, StateGraphViewer, and StateEvaluationTree into the TraceViewerFrame (as direct children). Remove the StateViewer.