A dazed-looking young man with long curly strawberry-blond hair wandered alone onstage and sat cross-legged, watching the still-chatting audience at the sold-out, opening night performance of University Theatre’s production of the 1960s rock musical “Hair.” More flower children dressed in fringed leather vests, crocheted tops and peasant skirts filtered through the seats handing out daisies and herbal joints.