content: exclude links to ip addresses

There is no good reason to link to an ip directly.

src/domutil.js

@@ -35,6 +35,9 @@ function isValidURL(url) {
     if (lastDot < 1) {
         return false;
     }
+    if (url.hostname.slice(lastDot + 1).match(/^[\d]+$/)) {
+        return false;
+    }
     if (url.hostname.slice(lastDot) === '.local') {
         return false;
     }