[status =] Eyelink(‘ReceiveFile’,[‘filename’], [‘dest’], [‘dest_is_path’])
If <src> is omitted, tracker will send last opened data file.
If <dest> is omitted, creates local file with source file name.
Else, creates file using <dest> as name. If <dest_is_path> is supplied and
uses source file name but adds <dest> as directory path.
returns: file size if OK, 0 if file transfer was cancelled, negative = error