FILEMENU - (C) Copyright Glenn B. Lawler, 1992. All Rights Reserved.
Usage: -Options FileSpec [MemFile]
Where: FileSpec specifies a drive, path, filename from
which the user selects.
The selected filename is written to the DOS StdOut.
If nothing is selected (user Escapes), nothing is written
to StdOut and ERRORLEVEL is set to 1.
MemFile is optional and is name of file to store selection.
On loading, if MemFile exists, it is loaded and used to
resume the same position in menu from previous run.