Add ZeroMQ support. Notify blocks and transactions via ZeroMQ

Continues Johnathan Corgan's work.
Publishing multipart messages

Bugfix: Add missing zmq header includes

Bugfix: Adjust build system to link ZeroMQ code for Qt binaries

src/Makefile.am

@@ -48,6 +48,9 @@ if ENABLE_WALLET
 BITCOIN_INCLUDES += $(BDB_CPPFLAGS)
 EXTRA_LIBRARIES += libbitcoin_wallet.a
 endif
+if ENABLE_ZMQ
+EXTRA_LIBRARIES += libbitcoin_zmq.a
+endif
 
 if BUILD_BITCOIN_LIBS
 lib_LTLIBRARIES = libbitcoinconsensus.la
@@ -157,7 +160,12 @@ BITCOIN_CORE_H = \
   wallet/db.h \
   wallet/wallet.h \
   wallet/wallet_ismine.h \
-  wallet/walletdb.h
+  wallet/walletdb.h \
+  zmq/zmqabstractnotifier.h \
+  zmq/zmqconfig.h\
+  zmq/zmqnotificationinterface.h \
+  zmq/zmqpublishnotifier.h
+
 
 obj/build.h: FORCE
 	@$(MKDIR_P) $(builddir)/obj
@@ -199,6 +207,17 @@ libbitcoin_server_a_SOURCES = \
   validationinterface.cpp \
   $(BITCOIN_CORE_H)
 
+if ENABLE_ZMQ
+LIBBITCOIN_ZMQ=libbitcoin_zmq.a
+
+libbitcoin_zmq_a_CPPFLAGS = $(BITCOIN_INCLUDES)
+libbitcoin_zmq_a_SOURCES = \
+  zmq/zmqabstractnotifier.cpp \
+  zmq/zmqnotificationinterface.cpp \
+  zmq/zmqpublishnotifier.cpp
+endif
+
+
 # wallet: shared between bitcoind and bitcoin-qt, but only linked
 # when wallet enabled
 libbitcoin_wallet_a_CPPFLAGS = $(BITCOIN_INCLUDES)
@@ -320,12 +339,15 @@ bitcoind_LDADD = \
   $(LIBMEMENV) \
   $(LIBSECP256K1)
 
+if ENABLE_ZMQ
+bitcoind_LDADD += $(LIBBITCOIN_ZMQ) $(ZMQ_LIBS)
+endif
+
 if ENABLE_WALLET
 bitcoind_LDADD += libbitcoin_wallet.a
 endif
 
 bitcoind_LDADD += $(BOOST_LIBS) $(BDB_LIBS) $(SSL_LIBS) $(CRYPTO_LIBS) $(MINIUPNPC_LIBS) $(EVENT_PTHREADS_LIBS) $(EVENT_LIBS)
-#
 
 # bitcoin-cli binary #
 bitcoin_cli_SOURCES = bitcoin-cli.cpp