In msg4867 of issue481, we looked into some unexplained errors that seem to be
caused by VAL taking excessive time/memory. For diagnosing things like these
more easily in the future, it would be helpful to add some more logging to the
driver script.

Suggestion: change the logging format in the driver script so that it
reports various time-related statistics, such as
- current date and time
- elapsed clock time since program started
- elapsed CPU time in subprocesses so far

This should be possible with a suitable configuration call to Python's
logging module.