We now run the Hydrogen render in a `child_process` so we can exit the whole render process. We still use the `vm` to setup the browser-like globals. With a `vm`, everything continues to run even after it returns and there isn't a way to clean up, stop, kill, terminate the vm script or context so we need this extra `child_process` now to clean up. I don't like the complexity necessary for this though. I wish the `vm` API allowed for this use case. The only way to stop a `vm` is the `timeout` and we want to stop as soon as we return.
Fix https://github.com/matrix-org/matrix-public-archive/issues/34
Eric Eastwood