FastSerializerHelper::singleElement/startElement internal API changed

[Kaganski Mike]

Hi!

This is just to notify those who might currently use 
FastSerializerHelper in patches being prepared.

Commit 1fe24bb1e2fbe44a4bf2c03297e259b3a18b1235 has modified the 
singleElement/startElement[NS] APIs by removing FSEND (which was a 
remnant of old C-style varargs implementation). So if you use these APIs 
in your ongoing work, please rebase.

-- 
Best regards,
Mike Kaganski