DOM loadHtml improvements
DOM loadHtml improvements

allows to load text-only HTML, and handles better more root elements in the document
ref https://github.com/peachpiecompiler/peachpie/issues/682

iolevel/peachpie-concept,iolevel/peachpie,peachpiecompiler/peachpie,peachpiecompiler/peachpie,iolevel/peachpie-concept,iolevel/peachpie,peachpiecompiler/peachpie,iolevel/peachpie,iolevel/peachpie-concept