Update libraries/Template.php

In partial view (header.php) I can't get the template title
<?php echo $template['title']; ?>
This is a fix
Update libraries/Template.php

Setting the "Cache-control" header twice overwrites the first because CI's default "$replace" parameter in CI_Output::set_header is TRUE.
The side effect of this is pages are not revalidated when navigating browser history.
Merge commit 'c0727e402d1134560bbcc88cef10e83cea98e1ea'