Improve symbol orphan detection
A symbol is also a orphan if the parent exists, but is stored inside the .kicad_sym file after the child. We read the file sequentally, so we can check it sequentially as well.
A symbol is also a orphan if the parent exists, but is stored inside the .kicad_sym file after the child. We read the file sequentally, so we can check it sequentially as well.