Clear screen after getting forward-to address

As pointed out by Keyop via irc, if the message has an attachment,
a comment is prompted for and since the "To:" prompt uses P_NOCRLF,
the first comment prompt was on the same line. So clear the screen, which
is what happens when the forwarded message has no attachment anyway.

exec/msglist.js

@@ -1066,6 +1066,7 @@ function list_msgs(msgbase, list, current, preview, grp_name, sub_name)
 								console.clearline();
 								var dest = prompt("To", "", K_NOCRLF);
 								if(dest) {
+									console.clear();
 									if(!bbs.forward_msg(list[current], dest))
 										alert("failed");
 								}