Makefile: start consulting node readline externs for type-checking.
repl: add src/js/repl/node.js as a better typed src/js/node/node_repl.js.
Makefile: add compile-node-repl and node-repl targets.
node: remove src/node/*. See src/js/{env,repl}.
runtime: no need for evalAndAdvance() methods to return anything.