WIP: PROOF-of-CONCEPT: Graceful restart
Closes #227 (closed)
Uses https://github.com/cloudflare/tableflip to fork a child process which inherits the listener file descriptors.
When testing: keep in mind that the forked process will effectively be a daemon, running the background, even if the original process was running in the terminal. This can be mildly confusing if you're unaware of it.