Python 3 compatibility

[noamkush]

No description provided.

[stephan-hof]

Many thanks for this contribution. I'll have a look at this soon.

However there is one thing to mention.

In python3 they fixed threading.Condition, which is used by Queue from the standard library. In python3 threading.Condition is not doing busy waiting any more.
So now boost_queue and Queue are using the same locking mechanics under the hood, which means they should have the same performance characteristics in threaded applications.

So my recommendation would be to use Queue from the standard library instead of boost_queue when you use python3.

[noamkush]

Well, my use case involves a time sensitive system with a high throughput queue. The boost implementation is still 15x faster on python 3.4/3.5 (haven't tested on 3.6) for non-blocking put/get.