Updated Spanish translation
Eradicate links and xrefs

These are all replaced by markdown ref links.
Remove tables from GFileAttribute docs
Remove a stray <em> tag
Remove a few leftover <simplelist>s
Remove a new literal tag that has crept in
Convert GVariantType table to a list
Docs: convert another table to a list
Docs: Remove an example tag that has snuck back in
Convert more xincluded examples to external links
Convert another table to a list
Strip out a remaining programlisting
Another stray litreal
Another stray <programlisting>
Remove some informalexamples
REmove another table
Convert remaining examples to links
Docs: Drop entities, switch away from sgml mode

Since all element markup is now gone from the doc comments,
we can turn off the gtk-doc sgml mode, which means that from
now on, docbook markup is no longer allowed in doc comments.

To make this possible, we have to replace all remaining
entities in doc comments by their replacement text, &amp; -> &
and so on.
Fix a misformatting in GVariant docs

The + at the beginning of the line was misinterpreted
as markdown for a list.
[l10n] Updated Italian translation.