Next generation API work in progress

I have roughed out enough of an API to do the first bunch of examples from the guide.  This is up to and including the Poller example.

The new API is in org.jeromq.api. The guide examples for the new API are in guide/newapi (just a temporary location...I couldn't think of a better package name).

So far, I've created:
ZeroMQContext
Socket (many methods copied and modified from the old API)
Poller
Message (this is not really ported over yet, as it still references ZFrame. Just a placeholder for things to come for multipart messages).

There is definitely a non-zero chance that I messed something up in here.  Feedback is welcome!