Also fix String methods' receivers to be T, not *T, so that var m f32.Mat32 s := fmt.Sprintf("m=%v", m) works. LGTM=crawshaw R=crawshaw CC=golang-codereviews https://golang.org/cl/147490043
Also fix the f32_test. LGTM=crawshaw R=crawshaw CC=golang-codereviews https://golang.org/cl/149310043