fix first point when z top offset and stock set

src/mode/cam/export.js

@@ -226,7 +226,6 @@
             //     nl.append(" ; ").append(comment);
             //     nl.append(" ; ").append(points);
             // }
-
             append(nl.join(''));
             points++;
         }

src/mode/cam/prepare.js

@@ -223,7 +223,7 @@
             // before first point, move cutting head to point above it
             // then set that new point as the lastPoint
             if (!lastPoint) {
-                let above = point.clone().setZ(zmax + zadd);
+                let above = point.clone().setZ(zmax + zadd + ztOff);
                 lastPoint = layerPush(above, 0, 0, tool.getNumber());
             }