Critic's Notebook: The Memory of Love's Refrain; Standards Lose Two New York Outlets. But the Music? They Can't Take That Away.
Stephen Holden's Critic's Notebook column says that the demise of WQEW-AM, only New York radio outlet for popular music predating rock, represents severing of vital link with shared cultural past and that planned closing of Rainbow and Stars, city's leading cabaret, is stunning and unfortunate coincidence; photos (M)