fix #H4028 - ':' sometimes doesn't work

User had
MSGTTYPE=norep "You see here"
and complained that once the message had been given while walking
over an object, using ':' to intentionally look at something would
end up doing nothing if its feedback was a repeat of "You see here".

Trying to classify which actions should deliberately override
no-repeat (or no-show) will be an ordeal.  This fixes the case for
the ':' command where the user obviously expects feedback.  I think
it could be done better but am settling for something quick and easy.

src/pline.c

@@ -87,9 +87,26 @@ VA_DECL(const char *, line)
         return;
     }
 
+    /*
+     * Normally the sequence is
+     *  caller: pline("some message");
+     *   pline: vsprintf + putstr + iflags.last_msg = PLNMSG_UNKNOWN;
+     *  caller: iflags.last_msg = PLNMSG_some_message;
+     * and subsequent code can adjust the next message if it is
+     * affected by some_message.
+     *
+     * But some callers can use last_msg to control handling of next
+     * message
+     *  caller: iflags.last_msg = PLNMSG_NOREP_OVERRIDE;
+     *  caller: pline("another message");
+     * to force another_message to be delivered even if is a repeat
+     * and user's MSGTYPE settings have classified it as don't-repeat.
+     */
+
     msgtyp = msgtype_type(line, no_repeat);
-    if (msgtyp == MSGTYP_NOSHOW
-        || (msgtyp == MSGTYP_NOREP && !strcmp(line, prevmsg)))
+    if ((msgtyp == MSGTYP_NOSHOW && iflags.last_msg != PLNMSG_NOSHO_OVERRIDE)
+        || (msgtyp == MSGTYP_NOREP && iflags.last_msg != PLNMSG_NOREP_OVERRIDE
+            && !strcmp(line, prevmsg)))
         return;
     if (vision_full_recalc)
         vision_recalc(0);