More cleanup in poll_shared specs
ZMQ.error_check should handle unknown errno more gracefully
Moved ZMQ::ErrorMap to ZMQ@error_map. There is no reason it should be public
Move error_map.rb to error_check.rb because ZMQ.error_check is the public API edifice

--HG--
rename : lib/0mq/error_map.rb => lib/0mq/error_check.rb