Inappropriate use of toUTF8String has been fixed in few more places.
XRef export improvements.
1.  XRef scenes are now exported as <instance_node> elements either
    in standalone <node> element with name "XRefs" or in node corresponding
    to scene element to which XRefed file is bound.
2.  "Include XRefs" option in export dialog is now visible and actually
    works. It controls whether referenced scenes are also exported
    - not everyone needs this feature and it can considerably extend
    export times...