Add network data for translations

[lehkost]

In order to gain insights into the translation networks, I propose to extract corresponding data for original authors and their translators. This, of course, only works if we have concrete authors (and no anonymity on either side of a translation).

For example, for this play: https://einakter.staging.dracor.org/lebrun-ich-irre-mich-nie-oder-der-raeuberhauptmann … we would collect this node/edge information:

• Q125304 [Label: Lebrun, Karl August] ➝ Q2066224 [Label: Théophile Marion Dumersan]
• Q125304 [Label: Lebrun, Karl August] ➝ Q3170056 [Label: Jean-Toussaint Merle]

All in all, source and target nodes in this directed network, would consists of all Q numbers of authors being part of a translation (source: original author[s]; target: translator[s], or maybe the other way round?).

For a proposed GEXF format output, edge information from above would translate to:

<edge id="Q125304|Q2066224" source="Q125304" target="Q2066224" weight="1"/>

Node value (example):

<node id="Q125304" label="Lebrun, Karl August">
  <attvalues>
    <attvalue for="gender" value="MALE"/>
  </attvalues>
</node>

Since we don't systematically collect gender information for original authors (yet?), we can probably do without at the beginning.