Don't generate any events from wxSpinCtrl and wxSpinCtrlDouble methods.

After the changes of r53758 wxMSW didn't generate any wxEVT_TEXT events but
this was still the case for the generic version (and hence for
wxSpinCtrlDouble under MSW too) and wasn't documented.

Fix all versions to avoid sending events for programmatic actions, add unit
tests checking this behaviour and document it.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74631 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/spinctrl.cpp

@@ -471,7 +471,9 @@ void wxSpinCtrlDouble::SetDigits(unsigned digits)
 {
     wxCHECK_RET( m_widget, "invalid spin button" );
 
+    GtkDisableEvents();
     gtk_spin_button_set_digits( GTK_SPIN_BUTTON(m_widget), digits);
+    GtkEnableEvents();
 }
 
 #endif // wxUSE_SPINCTRL