Regarding XML encoding:
It seems that libxml2 rewrites the following characters as XML entities:
hwloc already tells libxml2 to export as UTF-8. However, a quick check
seems to say that the output is not UTF8 when the locale isn't UTF8. We
may need to cdouble-check/clarify/fix this.
Or we can enforce ASCII-only for all strings. Should be OK for all
strings we import from the OS. Will need to be enforced for user-given
strings (object info attributes).