Fixups

* undefined variables in Markup.js
 * logic error preventing screenshot uploads
 * bitshift by negative value in spell
 * and i'm pretty sure i already added an exception handler at one point

pages/screenshot.php

@@ -107,7 +107,7 @@ class ScreenshotPage extends GenericPage
     {
         $this->imgHash = Util::createHash(16);
 
-        if (User::canUploadScreenshot())
+        if (!User::canUploadScreenshot())
         {
             $_SESSION['error']['ss'] = Lang::screenshot('error', 'notAllowed');
             return false;