Fix going to a msg number from viewing/reading msgs mode

In some uses (depending on the list order), typing a message number didn't
take you to the intended message.

Reported by Nelgin in IRC.

exec/msglist.js

@@ -1217,7 +1217,12 @@ function list_msgs(msgbase, list, current, preview, grp_name, sub_name)
 							break;
 						default:
 							if(typeof key == "number") {
-								current = key -1;
+								for(var i = 0; i < list.length; ++i) {
+									if(list[i].num == key) {
+										current = i;
+										break;
+									}
+								}
 								break;
 							}
 							break;