Additional safety data output

As always, for safety, good Whisker tasks write their data to two places: the database and a text file. In the brave new world of real databases and Python, this task writes its data to the proper database ‘live’, so the database is always up to date. When the task finishes, it reads that database and writes both structure and data to a text file. It does so in SQL format, so that a fully structured representation of all data relevant to a given session can easily be regenerated simply by replaying the SQL output into a fresh database.

The directory used for these files is one of the following, in descending order of priority: (1) the --outdir command-line parameter; (2) the WHISKER_SERIAL_ORDER_OUTDIR environment variable; (3) the current working directory from which the task was started.