[TIDOC-931] Return class attribute fragments for section URLs
[TIDOC-931] Rework some code
[TIDOC-931] Generate only if _escaped_fragment_ is set.
[TIDOC-931] Check for value existence
[TIDOC-931] Rework code.
Merge pull request #15 from bhatfield/tidoc-931

[TIDOC-931] Return class attribute fragments for section URLs