package.json keyword additions

This list has also been sorted, so pay close attention to the diff.

package.json.in

@@ -29,13 +29,18 @@
   },
 
   "keywords": [
+      "classes",
+      "classical",
+      "extend"
+      "gnu",
+      "inheritance",
+      "interfaces",
+      "mixins"
       "object oriented",
       "oo",
       "oop",
-      "classes",
-      "classical",
-      "interfaces",
       "protected members",
-      "inheritance"
+      "traits",
+      "visibility",
   ]
 }