Additions to allow consuming from multiple queues

Hi,

I have some changes in my fork which allow a PHP script to consume from multiple queues. It uses one connection per queue, and waits for messages using select() so as not to use CPU.

There is an outstanding issue which I'm sure would be easy to fix for someone who knows the Zend API better than I. You guessed it, there is a memory leak.

A simpler version of this code which uses PHP classes for most of the logic, and just a small amount of C code for the select() worked perfectly, however I decided to write the whole thing in C for simplicity installing and using the extension.

I'd appreciate it if you'd give me your comments, and let me know what the memory problem is.

Regards,

Duncan