Add triple export tasks

BSZGNDTopCooccurencesTriples:

This is a co-occurrence based cluster. Based on the
co-occurrence of GNDs per PPN, report the top N GNDs
for a GND.

Yields interesting results. Many of them relevant.
Biased towards the training source, in this case a single
library catalog. Less biased results could be expected
from a larger corpus.

DBPBSZTopSharedCategoriesTriples:

Take wikipedia categories, filter out relevant
categories that have linkage to GND and report
the top N GNDs that have the most categories in common.
Add triple export as example visualization