GH-114: Lock down bug tracker to developers only

All further conversation about bugs is supposed to happen on Github.
We still allow developers to edit the bug tracker, so they can clean
up.

We start by disallowing users to add patches.

www/bug.php

@@ -1109,7 +1109,9 @@
 <br>
 OUTPUT;
     }
-    echo "<p><a href='patch-add.php?bug_id={$bug_id}'>Add a Patch</a></p>";
+    if ($logged_in) {
+        echo "<p><a href='patch-add.php?bug_id={$bug_id}'>Add a Patch</a></p>";
+    }
 
     $pullRequestRepository = $container->get(PullRequestRepository::class);
     $pulls = $pullRequestRepository->findAllByBugId($bug_id);

www/patch-add.php

@@ -16,6 +16,13 @@
 // Authenticate
 bugs_authenticate($user, $pw, $logged_in, $user_flags);
 
+if (!$logged_in) {
+    response_header('Developers only');
+    display_bug_error('Only developers are allowed to add patches');
+    response_footer();
+    exit;
+}
+
 $canpatch = true;
 
 /// Input vars