Problem: ZAP status codes != 200 do not result in an appropriate monitor event (#2665)

* Problem: missing test for status code 300, inadequate assertion for status code 500

Solution: add test, change assertion (currently test fails)

* Problem: gcc compiler error deprecated conversion from string constant

Solution: declare variable as const

* Problem: in case of ZAP handler returning a status code other than 200, no appropriate event is emitted

Solution: immediately emit event after receiving reply from ZAP handler

* Problem: endpoint address is not included in zap-reply monitor event

Solution: added functions to retrieve endpoint address in zmq::i_engine and zmq::session_base_t
removed unused code block in zmq::stream_engine_t::next_handshake_command

* Problem: wrong formatting

Solution: fix formatting

* Problem: test fails because of EPIPE

Solution: add EPIPE/ECONNRESET/ECONNAGAIN handling for more test cases

src/session_base.hpp

@@ -97,6 +97,7 @@ namespace zmq
         int write_zap_msg (msg_t *msg_);
 
         socket_base_t *get_socket ();
+        const char *get_endpoint () const;
 
     protected: