Require reasons for checkpoints.

src/ScreenOptionsMaster.cpp

@@ -102,7 +102,7 @@ void ScreenOptionsMaster::HandleScreenMessage( const ScreenMessage SM )
 		// Override ScreenOptions's calling of ExportOptions
 		m_iChangeMask = 0;
 
-		CHECKPOINT;
+		CHECKPOINT_M("Starting the export handling.");
 
 		vector<PlayerNumber> vpns;
 		FOREACH_OptionsPlayer( p )
@@ -150,7 +150,7 @@ void ScreenOptionsMaster::HandleScreenMessage( const ScreenMessage SM )
 		if( m_iChangeMask & OPT_APPLY_SONG )
 			SONGMAN->SetPreferences();
 
-		CHECKPOINT;
+		CHECKPOINT_M("Transferring to the next screen now.");
 		this->HandleScreenMessage( SM_GoToNextScreen );
 		return;
 	}