Include Section marker only as appropriate in SxS header. Also, make node_type checking a bit more accurate
from_label -> type_from_label
Merge pull request #426 from khandelwal/delete_add_diff

Test for <ins> tags in interpretation headers (diff view)
Merge pull request #421 from cmc333333/section-symbol-sxs

Include section marker only as appropriate in SxS header