Fix text renderer to allow subclassing
Fix text renderer to allow subclassing

valsdav/plastex,mungerd/plastex,dav94/plastex,dav94/plastex,mungerd/plastex,valsdav/plastex,mungerd/plastex,mungerd/plastex,dav94/plastex,valsdav/plastex,dav94/plastex,valsdav/plastex