This handles version 1 and 2, and copes with the broken files
created by the Mac OS X "applesingle" command-line tool (which is
unable to decode the broken files it creates).
I get the sense that many AppleSingle files don't end with ".AS", so
the filespec includes "*.*" as well.
Some AppleSingle files don't include a filename. In that case, we
use the file's name as the entry name, minus any ".as" extension.
The current implementation doesn't convert from Unicode to Mac OS
Roman, so non-ASCII characters are mishandled unless the file was
generated by GS/ShrinkIt. (We assume version 1 AppleSingle files
use MOR name strings.)
Also, version bump to 4.0.0d3.
The file extraction dialog allows you to select file parts, so you
can choose to exclude resource forks or just extract disk images. If
you don't choose any parts, nothing will extract, and you get a
confusingly generic message about nothing matching the criteria.
This adds a specific error message for the case where no parts are
selected.
