[tei-council] age= of <person> & <personGrp>

[Syd Bauman]

> But either way, the documentation should be much clearer. Although
> I don't feel I'm the most qualified to do this, I will be happy to
> take a first crack at it soon. (But if someone else wants the task,
> speak up!)

As no one spoke up, I've had a go at this. Changes:

* role= and age= of <person> and <personGrp> are now all
  data.enumerated (they were a mixture of data.code and data.word+)

* new paragraphs in NDPERSE (13.3.2) briefly explain the attributes
  on <person>, including an explanation that projects should create a
  value list for age=, and an example of such a <valList>

* fixed examples in <particDesc> and <listPerson> tagdoc that had
  numeric values as value of age=.