Unmount cards if we time out. "Locking" and "finalizing" are the same;

merge them.  (They're both enabled and disabled in the same place.)
Pause the memory card thread during gameplay, so any changes will
wait until the current stage finishes (so we don't interrupt the player with
a noise and possibly skip).  Work on making MemoryCardManager::LockCards()
block if the card is in CHECKING.

stepmania/src/GameState.cpp

@@ -115,7 +115,6 @@ void GameState::Reset()
 	m_pCurStyle = NULL;
 	FOREACH_PlayerNumber( p )
 		m_bSideIsJoined[p] = false;
-	MEMCARDMAN->SetPlayersFinalized( false );
 	MEMCARDMAN->UnlockCards();
 //	m_iCoins = 0;	// don't reset coin count!
 	m_MasterPlayerNumber = PLAYER_INVALID;
@@ -230,11 +229,9 @@ void GameState::BeginGame()
 
 void GameState::PlayersFinalized()
 {
-	if( MEMCARDMAN->GetPlayersFinalized() )
+	if( MEMCARDMAN->GetCardsLocked() )
 		return;
 
-	MEMCARDMAN->SetPlayersFinalized( true );
-
 	MEMCARDMAN->LockCards();
 
 	// apply saved default modifiers if any