Allow the 'in-transit' attribute flag to be removed from msgs in any msgbase

If a msgbase internal code is passed on the command-line, use that msgbase
instead of 'mail' (where the use of the 'in-transit' flag is normally expected
to be seen). For Keyop.

exec/notransit.js

 /* notransit.js */
 
-/* Removes MSG_INTRANSIT attribute from messages in mail database */
+/* Removes MSG_INTRANSIT attribute from messages in mail (or other) msgbase */
 
 load("sbbsdefs.js");
 
-mail = new MsgBase("mail");
+mail = new MsgBase(argv[0] || "mail");
 if(!mail.open()) {
 	alert(mail.last_error);
 	exit();