LinkedList.tostring: minor touch-ups
LinkedList.tostring: minor touch-ups

* Use the _class_name instead of a hard-coded class-name when
  preparing the tostring() header

* touch up some comments

Signed-off-by: Gregory M. Turner <1f6d1f05bf03ff30afa6123e0bee2caa2da7cff0@be-evil.net>

Afforess/Factorio-Stdlib