Vanillicon Proxy

This is a fork of the original vanillicon plugin for vanilla forums. Likewise, it provides fun default user icons from vanillicon.com. However, VanilliconProxy introduces two new features:

1. Proxy: Icons are downloaded indirectly through your server. This enhances privacy for your users, since third-parties are not able to track them anymore.
2. Cache: Requested icons are cached on your server and they are then provided to your users without access to third-party servers. This enhances availability of your forum.

Please feel free to create issues or pull requests on GitHub. :-)