Generation numbers on TWENEX

[JONL at MIT-MC (Jon L White)]

1) ">" should be acceptable as a generation number, meaning roughly
   the same thing as when used a a second file name for ITS
2) default generation number for UWRITE and OPEN (with open option OUT)
   seems random - possibly defaulting the same as device or directory
   to the last one mentioned specifically in a UREAD or input OPEN
3) UFILE returns a list which consists of the temporary name instead of
   the final renamed name
4) (UREAD FOO BAR /8) should recognize the /8 as a generation number
   rather than a device name