Writings filtering

In the same vein than authors filtering (throwaway.py), @mariebizaislillig needs a script which searches for writings in the_writings table from a CSV containing writings identifiers titles. Script output should be 3 CSVs :

• one for writings that were found (ie. just 1 match)
• one for writings that were not found (ie. 0 match)
• one for writings for which more than 1 match was found