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.java

@@ -877,6 +877,10 @@ public class Un {
                 result.keyExtend = true;
             } else if (!arg.startsWith("-")) {
                 result.sourceFile = arg;
+            } else {
+                System.err.println("Unknown option: " + arg);
+                printHelp();
+                System.exit(1);
             }
         }
         return result;