It was a crowd without a leader. Yet the chorus from hundreds outside 1 World Trade Center early Monday shifted seamlessly from the “Star Spangled Banner” to “God Bless America” to the pledge of allegiance and back--anything would do.All along Church Street near Ground Zero, a mass of New Yorkers spilled into the streets to mark the death of Osama bin Laden, architect of the mass killing at that very spot nearly a decade ago.