Ensure the Group Offset is applied when Reloading a Song from Disk

src/Song.cpp

@@ -481,6 +481,7 @@ bool Song::ReloadFromSongDir( RString sDir )
 		return false;
 	copy.RemoveAutoGenNotes();
 	*this = copy;
+	m_SongTiming.m_fBeat0GroupOffsetInSeconds = GetGroup()->GetSyncOffset();
 
 	/* Go through the steps, first setting their Song pointer to this song
 	 * (instead of the copy used above), and constructing a map to let us
@@ -489,10 +490,14 @@ bool Song::ReloadFromSongDir( RString sDir )
 	for( std::vector<Steps*>::const_iterator it = m_vpSteps.begin(); it != m_vpSteps.end(); ++it )
 	{
 		(*it)->m_pSong = this;
-
 		StepsID id;
 		id.FromSteps( *it );
 		mNewSteps[id] = *it;
+
+		// Reapply the Group Offset if the steps have their own timing data.
+		if( mNewSteps[id]->m_Timing.empty() )
+			continue;
+		mNewSteps[id]->m_Timing.m_fBeat0GroupOffsetInSeconds = GetGroup()->GetSyncOffset();
 	}
 
 	// Now we wipe out the new pointers, which were shallow copied and not deep copied...