improved TEI detection (also check xmlns, also detect correctly if xml prolog is missing)
improved TEI detection (also check xmlns, also detect correctly if xml prolog is missing)

ubtue/ub_tools,ubtue/ub_tools,ubtue/ub_tools,ubtue/ub_tools,ubtue/ub_tools,ubtue/ub_tools,ubtue/ub_tools,ubtue/ub_tools