rb.script lets a script end itself or start over from its file. A script
reaches for it when its work is done, when it finds a state it cannot handle,
or when it wants to pick up an edited file.
This script does its setup once, then stops itself:
When the script stops, its
rb.on("stop") handlers run and every key and
button it still holds is released.
exit(reason) and die(reason) are global aliases of rb.script.exit.