Add SIGTERM and SIGINT signal handlers so that we run the exit handlers
before exiting when getting these signals. Fixes an issue where we
couldn't run vi after CTRL+C'ing node because the stdin fd was left
non-blocking.

needs tests (particularly for pipeline situations)

This was meant to find a bug in setTimeout, but there doesn't seem to be
one. So this test can no help to prevent future regressions.

Though, this should probably be an option to sys.inspect and be set by REPL.