Add a warning when connecting without disconnecting which can cause memleaks

src/zm_monitor.cpp

@@ -880,6 +880,10 @@ std::shared_ptr<Monitor> Monitor::Load(unsigned int p_id, bool load_zones, Purpo
 }
 
 bool Monitor::connect() {
+
+  if (mem_ptr != nullptr) {
+    Warning("Already connected. Please call disconnect first.");
+  }
   Debug(3, "Connecting to monitor.  Purpose is %d", purpose);
 #if ZM_MEM_MAPPED
   snprintf(mem_file, sizeof(mem_file), "%s/zm.mmap.%d", staticConfig.PATH_MAP.c_str(), id);