Non-ASCII characters not handled properly

Created by: Ede123

Importing the old unittests (#24) uncovered an issue with non-ASCII characters

See unittests/utf8.svg

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<svg xmlns:xlink="http://www.w3.org/1999/xlink" 
   xmlns="http://www.w3.org/2000/svg">
  <desc>ú</desc>
</svg>

for the failing example