[Python-3000] C API cleanup str

[Thomas Heller]

Martin v. Löwis schrieb:
>> One issue with just putting this in the C API docs is that I believe
>> (tell me if I'm wrong) that these haven't been kept up to date in the
>> struni branch so we'll need to make a lot more changes than just this
>> one...
> 
> That's certainly the case. However, if we end up deleting the str8
> type entirely, I'd be in favor of recycling the PyString_* names
> for Unicode, in which case everything needs to be edited, anyway.

PyText_*, maybe?

Thomas