all these bells and whistles seems to be hamburg specific.
modules_type in you build seems to always be 'mod', so no need
to track it.

the whole source_config things is not use in our build either.

note: this is a rough cut... there is probably left-over to trim as
a consequence of this.

Although "style" does not seem to be valid attribute in HTML 3.2
it is harmless to export it. This simplifies the code and makes
the exported HTML more useful in modern browsers.

Previously border settings were not available in paragraph format dialog
when HTML export format was "HTML 3.2". This was confusing since documents
with borders could still be imported and you could even access the border
dialog with suitably configured shortcut key.

With SvULongs replaced by std::vector std::find can be used in IsRemoved_Impl IsAdded_Impl

Be careful here.  It's not right to mark the whole expression #REF!
when only one of the references is invalid.  fdo#37391 is about
invalidating a single reference, not a whole formula expression.