[glchen]

1. Allow SGC cards to be added to the PSA registry.
2. Allow SGC cards to be reholdered into PSA slabs at the same grade. Before folks scream that SGC cards may not cross over at the same grade as PSA, perhaps mark the new PSA flip in a way that shows that the card was a SGC reholder, e.g., add a leading "S" to the new cert number. Also, don't allow 9.5/10's to be reholdered at the same grade, but they must go through a crossover process.