Rearrange setting time & freq formats for numeric controls...

... Just one low-level function for each that simply sets; just one high-level
function for each that also pushes notifications; and to make that work,
toolbars need some rewriting to avoid recursion when the notifications they
post come back to them.

src/TrackPanel.h

@@ -306,10 +306,6 @@ class AUDACITY_DLL_API TrackPanel final
 
    void DisplaySelection();
 
-   // These two are neither used nor defined as of Nov-2011
-   // void SetSelectionFormat(int iformat)
-   // void SetSnapTo(int snapto)
-
    void HandlePageUpKey();
    void HandlePageDownKey();
    AudacityProject * GetProject() const override;