Changed xml-model from tei_all to custom syriaca

<?xml-model
href="http://www.tei-c.org/release/xml/tei/custom/schema/relaxng/tei_all
.rng" schematypens="http://relaxng.org/ns/structure/1.0"?>

replaced with

<?xml-model
href="http://syriaca.org/documentation/syriaca-tei-main.rnc"
type="application/relax-ng-compact-syntax"?>