message: xlate arguments for ext commands, fixes
diff: @@ -79,7 +79,7 @@ function executionLoop() {
  if (isExtCommand(command)) {
  let upperCase = command.charAt(0).toUpperCase() + command.slice(1);
  return doDelay().then(() => (
  - (extCommand["do" + upperCase](target, value))
  + (extCommand["do" + upperCase](xlateArgument(target), xlateArgument(value)))
  .then(() => {
  PlaybackState.setCommandState(id, PlaybackStates.Passed);
  }).then(executionLoop)
  