Implement queue based on gipc

[qinxuye]

As gipc.pipe can only be used by one process mentioned in #11 , it could be quite non-trivial to send a message from one process to another.

I think the queue implementation to gipc is quite useful for me.

Background

I have implemented an Actor model system based on gipc, A few processes could be forked by gipc.start_process, each process has a duplex pipe connected to the main process, the actors created may locate on different processes, hence if one actor wants to send a message to another, the serialized message needs to be passed to the main process via the gipc pipe, the main process needs to deserialize part of the serialized message to check which destination process is, and then write the serialized message to the process via the specified gipc pipe, this is quite complicated and low-efficient.

If there is a queue, the number of queue can be equal to the process size, a message from one actor could be serialized and written directly into the specified queue, this could make the code more neater and efficient in my opinion.

Thus I wonder if there is any plan for the queue implementation, thanks.