Feminist art is the most important art movement since World War II, writes Blake Gopnik. “More than any other 20th-century movement, feminism pushed back against the art-for-art’s-sake attitudes of modernist abstraction. It pushed instead for work that talked about crucial issues in the world outside. Ever since feminism, in all areas of artmaking, the message has mattered as much as the medium.” WaPo produces a section of stories…