Complete StructuredData parity and parser hardening (#37)

crates/libremetaverse-structured-data/src/xml_codec.rs

@@ -296,6 +296,9 @@ impl<'a> Parser<'a> {
             if self.at_end(name) {
                 break;
             }
+            if self.rest().is_empty() {
+                return Err(self.error("unterminated XML LLSD scalar"));
+            }
             if self.rest().starts_with("<!--") {
                 self.skip_comment()?;
                 continue;