Correct xml header and character encoding

Hi.

When working with multiple sites this plugins is gre8, however i miss 2 simple changes.

When accessing the rss feed its not served with either correct header nor any character encoding. Following html5 i would like to see it with utf-8

in index.php line 421 function output_rss change

echo '<?xml version="1.0"?>';

to

header ("Content-Type:text/xml");
echo '<?xml version="1.0" encoding="UTF-8"?>';

https://ww.wp.xz.cn/plugins/simple-history/