Keep the order in which we saw files when matching filenames.
Fix a call to truncate-tables which didn't get the memo.

In passing, have a default identifier-case of :downcase.
Fix *csv-path-root* at run-time.

When using LOAD CSV it's possible to load from filename matching a
regular expression, but for that to work the *csv-path-root* needs to be
properly setup at run-time.
Document FILENAMES MATCHING option.