Update underline after updating refresh rate.

Put the default refresh back to "default"; some systems apparently
think they have refresh rates that they don't.

Make refresh "0" and max "1", so people with existing INI files keep
"default".

stepmania/src/PrefsManager.cpp

@@ -15,6 +15,7 @@
 #include "GameManager.h"
 #include "GameState.h"
 #include "RageException.h"
+#include "RageDisplay.h"
 
 
 PrefsManager*	PREFSMAN = NULL;	// global and accessable from anywhere in our program
@@ -29,7 +30,7 @@ PrefsManager::PrefsManager()
 #endif
 	m_iDisplayResolution = 640;
 	m_iTextureResolution = 1024;
-	m_iRefreshRate = 0;
+	m_iRefreshRate = RageDisplay::REFRESH_DEFAULT;
 	m_bIgnoreJoyAxes = false;
 	m_bOnlyDedicatedMenuButtons = false;
 #ifdef _DEBUG