Update utf8proc.[ch] to use the version now
maintained by the Julia Language project
(https://github.com/JuliaLang/utf8proc/blob/master/LICENSE.md).
The license for the previous version was
unacceptable for the Debian and Ubuntu release
systems. The new version both updates the code
and addresses the license issue.
It turns out that the utf8proc software we are using
was turned over to the Julia Language developers
and the license terms changed to allow modification.
(https://github.com/JuliaLang/utf8proc/blob/master/LICENSE.md).
So the fix here is as follows:
1. Wrap the library with a fixed interface: libdispatch/dutf8.c
and include/ncutf8.h.
2. Replace the existing utf8proc code with the new version
from https://github.com/JuliaLang/utf8proc.
3. Add a couple more test cases: nc_test/tst_utf8_validate.c
and nc_test_utf8_phrases.c. If/when I can find a usable
normalization test, I will incorporate that later.
This consists of a persistent attribute named
_NCProperties plus two computed attributes
_IsNetcdf4 and _SuperblockVersion.
See the 'Provenance Attributes' section
of docs/attribute_conventions.md for details.
