Added options to the Smarty extension that configure the text that is us...

...ed to replace quotes. This makes it possible to use the correct quotes in languages other than English.

Use e.g. the following config for correct German quotes:

    extensionConfigs = {
        'smarty': [('smart_lsquo', '&sbquo;'), # sb is not a typo!
                   ('smart_rsquo', '&lsquo;'),
                   ('smart_ldquo', '&bdquo;'),
                   ('smart_rdquo', '&ldquo;')]
    }