Text.CSL.Output.Pandoc:  Added Span to traversal routines.
Text.CSL.Output.Pandoc:  Added Span to traversal routines.

This fixes a bug in which periods would sometimes not be
inserted at the end of a title (if it ended with a nocase span).

adunning/pandoc-citeproc,jgm/pandoc-citeproc,jkr/pandoc-citeproc