rename and comment top and noodle fields

src/kiri-mode/fdm/post.js

@@ -210,9 +210,9 @@ FDM.doTopShells = function(z, top, count, offset1, offsetN, fillOffset, opt = {}
         top.poly = top.poly.clone(false);
     }
 
-    top.shells = [];
-    top.fill_off = [];
-    top.fill_lines = [];
+    top.shells = [];        // strategies output shells here
+    top.fill_off = [];      // offset from innermost shell for infill
+    top.fill_lines = [];    // fill lines inside fill_off
 
     let last = [],
         gaps = [];

src/kiri-mode/fdm/slice.js

@@ -41,7 +41,7 @@ const POLY = polygons,
         fill: { check: 0x008855, face: 0x008855, line: 0x008855, opacity, lopacity, fat },
         infill: { check: 0x3322bb, face: 0x3322bb, line: 0x3322bb, opacity, lopacity, fat },
         inset: { line: 0x555555, check: 0x555555 },
-        part: { line: 0x999999, check: 0x999999, face: 0  },
+        part: { line: 0x777777, check: 0x777777, face: 0  },
         thin: { check: 0xbb8800, face: 0xbb8800, line: 0xbb8800, opacity, lopacity, fat },
     }),
     PROTO = Object.clone(COLOR),