WIP/ENH: reading older Stata versions, #11526
A simple file seems to read OK if we just treat it like other "old format" (version 104-115) files.  However I do not currently have any documentation for this format.  The only relevant resource I can find is the file `foreign/src/stataread.c` in the R `foreign` package sources:

https://cran.r-project.org/src/contrib/foreign_0.8-66.tar.gz

It suggests some special handling for version 111 but I haven't had time to figure out exactly what it is doing.
- [x] closes #11526 
- [x] tests added / passed
- [x] passes `git diff upstream/master | flake8 --diff`
- [x] whatsnew entry
