This update fixes custom blocks (noteblock based) interactions with pistons. Thanks to Boy0000 for the pull request. It also fixes an issue with click action (thanks to iGabyTM).
Oracle, the company that hosts the default polymath server had a problem with the IPs today. I managed to put everything back in place but it may have caused some inconvenience on the loading of the textures. I want to apologize to you and I will start writing a tutorial to set up your own Polymath server.