TCPServer fixes

- Proper shutdown sequence, uv_close() must be called from the event loop thread
- Moved start_listening() to child class constructor because it must be ready before it can listen on sockets
- Added simple memory leak detector for Windows. Linux users can enjoy the leak sanitizer

CMakeLists.txt

@@ -53,6 +53,7 @@ set(SOURCES
 	src/keccak.cpp
 	src/log.cpp
 	src/main.cpp
+	src/memory_leak_debug.cpp
 	src/mempool.cpp
 	src/p2p_server.cpp
 	src/p2pool.cpp