fixed topic name in posts so that it came out right; fixed SIG welcome

page so that it generates correct URL; repaired a security hole (well, not
really, but a PERCEIVED security hole) regarding accounts that have been
created but not yet confirmed

src/com/silverwrist/venice/servlets/format/TopicPosts.java

@@ -405,4 +405,13 @@ public class TopicPosts implements JSPRender
 
   } // end getNumPostsPerPage
 
+  public boolean displayAttachmentInNewWindow(TopicMessageContext msg)
+  {
+    if (!(msg.hasAttachment()))
+      return false;
+    String type = msg.getAttachmentType();
+    return (type.startsWith("text/") || type.startsWith("image/"));
+
+  } // end displayAttachmentInNewWindow
+
 } // end class TopicPosts