- Update to new upstream release 3.9.1
* Package missing header file

- Update to new upstream release 3.9
* Add missing includes and guard to public include files
* For filesystem/filehandle-related functions, io.h should now be
included in userspace programs instead of misc.h
* hxdirstamp: new development helper program for library users
* io: new functions HXio_full{read,write}