- access most globals by their $_XYZ['varname'] name

- fix some code errors and typos (missing $ in front of variable names
and so on)
- fixed a lot of warnings that would have been thrown when error_reporting
is set to show notices (if(isset($variable))) instead of if($variable) for
example)

deletecomment.php

@@ -67,7 +67,7 @@ if($email)
     $fullAppName = "Application: ".lookupAppName($appId)." Version: ".lookupVersionName($appId, $versionId);
     $ms .= APPDB_ROOT."appview.php?appId=$appId&versionId=$versionId\n";
     $ms .= "\n";
-    $ms .= ($current->username ? $current->username : "Anonymous")." deleted comment from ".$fullAppName."\n";
+    $ms .= ($_SESSION['current']->username ? $_SESSION['current']->username : "Anonymous")." deleted comment from ".$fullAppName."\n";
     $ms .= "\n";
     $ms .= "Subject: ".$subject."\n";
     $ms .= "\n";