* Problem: Poller's handler not aware of event type.
It was possible to register a handler for more than one event types but
impossible to distinguish which event is being handled.
Now events are passed to a handler.
Besides that some other changes:
* new test covering changes in the poller
* modified existing tests to cover changes in the poller
* defined handler_t in poller_t scope for more convinient use
and simpler code
* helper loopback binder to be re-used in tests
* Problem: CMake build fails on Windows
Issue #199
It seems that with GCC on Linux <array> is implicitly included
by one of stl includes already in zmq.hpp but it breaks on Windows
with Visual Studio.
Adding explicit include for array.
Can not verify right now but this change is a good practice
so creating a pull request.
* Poller: array include not between C++11 guards
@sigiesec's recent commits with gtests and basics tests for zmq
types (thanks for that!) makes it too convinient to not add some more tests.
* Adding some simple tests for poller_t
* Stripped whitespaces from poller implementation.
