Fix: catch unknown flags in all remaining implementations

Added unknown flag validation to session command in:
awk, clj, cob, erl, ex, f90, forth, fs, lisp, ml, pro, r, scm, tcl, Java

Now all 42+ implementations properly reject unknown flags with
'Unknown option' error instead of making confusing API requests.

un.cob

@@ -376,6 +376,16 @@
                    ELSE
                        MOVE WS-ARG3 TO WS-INPUT-FILES
                    END-IF
+               ELSE
+                   IF WS-ARG3(1:1) = "-"
+                       STRING "Unknown option: " FUNCTION TRIM(WS-ARG3)
+                           DELIMITED BY SIZE INTO WS-ERROR-MSG
+                       END-STRING
+                       DISPLAY WS-ERROR-MSG UPON SYSERR
+                       DISPLAY "Usage: un.cob session [options]" UPON SYSERR
+                       MOVE 1 TO RETURN-CODE
+                       STOP RUN
+                   END-IF
                END-IF
                ACCEPT WS-ARG3 FROM ARGUMENT-VALUE
            END-PERFORM.