Force database commit before generating a report

Since the journal mode is WAL, database changes are saved only every 1,000 page changes (cf https://www.sqlite.org/compile.html#default_wal_autocheckpoint and https://www.sqlite.org/c3ref/wal_checkpoint_v2.html).

But it may be better to force commiting in some cases:

• before generating a report: to have all details in databases, else it is useless
• before exiting the app: already done by default