Fix an issue with the cursor sometimes disappearing when a patch was received

Update CodeMirror to the latest version (5.13.2)

www/code/codemirror-5.13.2/bower.json

@@ -0,0 +1,17 @@
+{
+  "name": "codemirror",
+  "main": ["lib/codemirror.js", "lib/codemirror.css"],
+  "ignore": [
+    "**/.*",
+    "node_modules",
+    "components",
+    "bin",
+    "demo",
+    "doc",
+    "test",
+    "index.html",
+    "package.json",
+    "mode/*/*test.js",
+    "mode/*/*.html"
+  ]
+}