Each subdirectory represents a set of related tests.

Each one contains:
 * one or more files with names beginning "input-"

   The prefix will be stripped and they will be copied
   into a new directory before beginning the test.
   The script will run from this directory.

 * a file "command"

   giving the parameters to bernard

 * one or more files with names beginning "output-"

  Each of these is a test.  Its contents will be compared
  with a file of the same name in the new directory.
  "output-stdout" is a special case; it represents whatever
  was printed to stdout.
  The comparison is exact, except for the "PO-Revision-Date"
  header.
