added cs:text

After sleeping on it, I decided to stick with my suggestion from last
night. So, simple change; I just added a cs-text pattern to the

cs-text =
element text {
> attribute idref { cs-text-ids })
cs-text-ids = “in”
> “available-from”
> “originally-published-as”

I’m a little uneasy about this again, because it means the schema has
to be in sync with any localizing. For now, I’ll leave this, but
reserve the right to change my mind, probably depending on how Simon
and I feel it works out practically. In any case, I like the cs:text
element and think that will stay. I’m just not sure about localization
in general.