create new api for parsing json incrementally.

[zhwaaaaaa]

I hope Jackson can parse json incrementally like yajl
Now I must keep all of the data of json message in memory and parse them in the situation of NIO. I think that it is perfect if Jackson can parse json incrementally when receiving partial data of a whole json message.

[cowtowncoder]

Jackson JsonParser only decodes specific next event and never keeps the whole document in memory.
Caller just iterates over events with JsonParser.nextToken() to extract whatever content they need.
There is even asynchronous (non-blocking) alternative.

So I am not sure what is being asked here, above and beyond what already exists.