Upgrade unbound library

These files were pulled from the 1.6.3 release tarball.

This new version builds against OpenSSL version 1.1 which will be
the default in the new Debian Stable which is due to be released
RealSoonNow (tm).

external/unbound/libunbound/python/doc/examples/example7.rst

@@ -1,18 +1,33 @@
 .. _example_idna:
 
-=================================================
 Internationalized domain name support
-=================================================
+=====================================
 
 Unlike the libUnbound, pyUnbound is able to handle IDN queries.
 
-..	literalinclude:: example7-1.py
-	:language: python
+Automatic IDN DNAME conversion
+-------------------------------
 
-If we use unicode string in :meth:`unbound.ub_ctx.resolve` method, the IDN DNAME conversion (if it is necessary) is performed on background.
+If we use unicode string in :meth:`unbound.ub_ctx.resolve` method,
+the IDN DNAME conversion (if it is necessary) is performed on background.
 
-..	literalinclude:: example7-2.py
-	:language: python
+Source code
+...........
 
-The :class:`unbound.ub_data` class contains attributes suffix which converts the dname to UTF string. These attributes have the '_idn' suffix.
-Apart from this aproach, two conversion functions exist (:func:`unbound.idn2dname` and :func:`unbound.dname2idn`).
+.. literalinclude:: example7-1.py
+    :language: python
+
+IDN converted attributes
+------------------------
+
+The :class:`unbound.ub_data` class contains attributes suffix which converts
+the dname to UTF string. These attributes have the ``_idn`` suffix.
+
+Apart from this aproach, two conversion functions exist
+(:func:`unbound.idn2dname` and :func:`unbound.dname2idn`).
+
+Source code
+...........
+
+.. literalinclude:: example7-2.py
+    :language: python