Common reorg (#8025)

* Re-organize common folder

* fix: Correct paths in tests

* fix: move new content to proper folder

* chore: Move audio folder to assets

* Move sprites to sprites assets directory

* Move css sprites to assets directory

* Split out readmes for common code and sprites

* Move images to assets directory

* Move destinatin of shared browserified file

* remove unused file

* move compiled js to client-old

* Fix karma tests

* fix: Correct paths for sprites

website/common/script/fns/predictableRandom.js

@@ -0,0 +1,24 @@
+import _ from 'lodash';
+
+// Because the same op needs to be performed on the client and the server (critical hits, item drops, etc),
+// we need things to be "random", but technically predictable so that they don't go out-of-sync
+
+module.exports = function predictableRandom (user, seed) {
+  if (!seed || seed === Math.PI) {
+    let stats = user.stats.toObject ? user.stats.toObject() : user.stats;
+    // These items are not part of the stat object but exists on the server (see controllers/user#getUser)
+    // we remove them in order to use the same user.stats both on server and on client
+    stats = _.omit(stats, 'toNextLevel', 'maxHealth', 'maxMP');
+
+    seed = _.reduce(stats, (accumulator, val) => {
+      if (_.isNumber(val)) {
+        return accumulator + val;
+      } else {
+        return accumulator;
+      }
+    }, 0);
+  }
+
+  let x = Math.sin(seed++) * 10000;
+  return x - Math.floor(x);
+};