error+runtime: hide r5js.IncorrectNumArgs behind a factory function.
error+runtime+misc: hide r5js.InternalInterpreterError behind a factory function.
error+runtime+test: hide r5js.ArgumentTypeError behind a factory function.
error: remove provides of two no longer extant errors.
error+io: remove no longer used r5js.IOError.
error+runtime: hide r5js.IllegalEmptyApplication behind a factory function.
error+runtime+test: hide r5js.ImmutableError behind a factory function.
error+runtime+misc: hide r5js.MacroError behind a factory function.