Initial LibreOffice GEDCOM import filter

The filter goes further, and after invoking ged2dot as a library, it
converts the dot to an svg, then uses the internal SVG import filter of
LibreOffice to actually present something to the user; all this in a
transparent way.
lo: add loader that registers the import filter

One would hope that all the sys.path and exception cathing tricks used
here will be unnecessary in the future, but for now let's just stick to
what LO 4.2 provides, that's new enough already.