Revert #1682 (three-axis milling) (#1715)

Thanks @bherbruck.

assets/icons/ui/source/icons.rs

@@ -142,19 +142,6 @@ pub(crate) fn paint_with(p: &Painter, r: Rect, name: &str, ink: Color32, fill: C
     let pen = Pen { p, r, ink, fill, accent, w: (r.width() / 24.0 * 1.4).max(1.0) };
     let a = pen.accent;
     match name {
-        "cam_path" => {
-            pen.closed(&[(3.0, 4.0), (21.0, 4.0), (21.0, 20.0), (3.0, 20.0)], ink);
-            pen.line(&[(5.0, 7.0), (18.0, 7.0), (18.0, 11.0), (6.0, 11.0), (6.0, 15.0), (18.0, 15.0)], a);
-        }
-        "cam_generate" => {
-            pen.line(&[(3.0, 5.0), (10.0, 5.0), (10.0, 11.0), (3.0, 11.0), (3.0, 18.0), (10.0, 18.0)], ink);
-            pen.poly(&[(14.0, 5.0), (22.0, 12.0), (14.0, 19.0)], a, a);
-        }
-        "cam_verify" => {
-            pen.iso_box(2.0, 9.0, 9.0, 6.0, 7.0);
-            pen.line(&[(12.0, 16.0), (15.0, 19.0), (22.0, 9.0)], a);
-        }
-
         "sketch" => {
             pen.poly(&[(3.0, 14.0), (13.0, 9.0), (21.0, 13.0), (11.0, 18.0)], pen.fill, ink);
             pen.line(&[(7.0, 13.0), (16.0, 4.0), (18.0, 6.0), (9.0, 15.0), (6.5, 15.5), (7.0, 13.0)], a);