Auto multi-query support

[fooling]

Unlike #2 , multi-query is a way to send several SQLs in a single request.
SQLs are spilited by ";"
We want a way to automaticly collect SQLs and send several SQLs together, then transparently give them back to upper layer.

ONLY a few situation can benifit from this
because there are potential deadlocks when doing this:

updateA(lock)--------------------------------updateB-------------
updateB(lock)--------------------------------updateA(* DEADLOCK *)-----

---

com.mysql.jdbc can achieve sending SQLs this way via addBatch() and set allowMultiQuery field to true,

But we want a automatic way of using it.
User should not know the details downside.