node: use r5js.EvalAdapter#schemeValueToWriteString for repl printing.
eval+test: symbols should display without quotes. Add tests.
test: remove two duplicate expectations.
eval+misc: shorten r5js.EvalAdapter function names.
eval: reduce code duplication in r5js.EvalAdapter functions.
eval+test: better test coverage for external reprs of recursive types.
eval+test: re-support dotted lists in string output.
test: test writing recursive types to JS strings.