fixes #373 ask a longer random string

to openssl_random_pseudo_bytes, to avoid reaching the base64 trailing "=" signs

include/functions_session.inc.php

@@ -71,7 +71,7 @@ function generate_key($size)
       str_replace(
         array('+', '/'),
         '',
-        base64_encode(openssl_random_pseudo_bytes($size))
+        base64_encode(openssl_random_pseudo_bytes($size+10))
         ),
       0,
       $size
@@ -260,4 +260,4 @@ function pwg_unset_session_var($var)
   return true;
 }
 
-?>
+?>