When using DIRECTORY, the proper pattern to use to get all files
is #p"*" and not #p"*.*" on CLISP and GCL.
This is the opposite of other CL implementations, that
match everything with #p"*.*" and only files without extension with #p"*",
which seems more in line with the CLHS, though counter-intuitive wrt to POSIX.
Now the proper pattern to match all files with TRANSLATE-PATHNAME and
with logical pathnames is still #p"*.*" or #p"*.*.*".
Therefore, we introduce a new parameter *wild-file-for-directory*,
as distinguished from *wild-file*, for notable use with DIRECTORY-FILES.