Let's develop a platform for extension distribution [Repository open]

Hi @spockfish, This is what we need for the runner as well.

Do you know if it catches the case of a core update? After a core update I always have the issue that the node is still running (the process is there) but the pinging has stopped, causing the extension to no longer appear in the extension list.

@danny, is there a possibility to set a callback on the pinging mechanism, or should an extension survive a core update?