George Mason University’s Theater of the First Amendment is about to present the world premiere of “Stay,” an innovative collaborative work that deals with impermanence. “Stay” has been created by two women who teach at George Mason, playwright Heather McDonald and choreographer Susan Shields. “Heather and I had both been at GMU for years and we knew of each other’s work, but we had never met,” says Shields. “When we finally did meet it turned out we had both been through some similar experiences.”