h5 directive repeated

[James Taylor]

There seems to be a problem with having two of the same h5 headings in the same section, e.g.,

[hstuff](#h "h5:")

#####  h

         some code

###### h

        some more code

[James Taylor]

Also need to examine the case of the directive defined but never utilized. Ideally, it should return an empty augmented array.

[James Taylor]

Done and tested for.