Fix Usage error for scripts/set-version.sh
documented how to write tests and easily bump version numbers
REPL: command to automatically reevaluate last expression in the REPL
REPL: command to automatically reevaluate last expression in the REPL

- when the "repeat last expression" REPL command is active
- when the user sends a form tom evaluate to the REPL
- if the form evaluated without error
- then the last expression evaluated from the REPL input is evaluated again