cor -> core
move reindex from __main__ to indexing
Include timestamps in log messages
Send left-over data to Solr after iterating over a Querys results

even if the data is not large enough for a complete batch.
Enable server side cursors
add an example config file
Allow splitting up the work into batches

This makes the import process a bit faster when importing multiple
entity types in case importing one tpye is already finished and more
threads can be used to import the other ones