Description:
------------
newlines in attributes are allowed (htmlentities also does not 
convert newlines to 
 ) but they'll be removed when using 
simplexml.

Reproduce code:
---------------
$xml = new SimpleXMLElement(
'<?xml version="1.0" encoding="UTF-8" standalone="yes"?><str val="Line 1
Line2
Line3"/>'
);

echo $xml->asXML(); 


Expected result:
----------------
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<str val="Line 1
Line2
Line3"/>


Actual result:
--------------
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<str val="Line 1 Line2 Line3"/>