Heavy work on IPC.

We will now have a broker (aqhome-data) which stores data and distributes
value change messages among connected clients.
aqhomed will connect to that broker and send its values there.
aqhome-mqtt will also connect to the broker and send its values there.
Other clients can later connect to check for changes and react according
to rules.

apps/aqhome-data/c_getlastdatapoint.h

@@ -0,0 +1,25 @@
+/****************************************************************************
+ * This file is part of the project AqHome.
+ * AqHome (c) by 2023 Martin Preuss, all rights reserved.
+ *
+ * The license for this file can be found in the file COPYING which you
+ * should have received along with this file.
+ ****************************************************************************/
+
+#ifndef AQHOME_DATA_C_GETLASTDATAPOINT_H
+#define AQHOME_DATA_C_GETLASTDATAPOINT_H
+
+
+#include "./aqhome_data.h"
+
+
+void AqHomeData_HandleGetLastDataPoint(AQHOME_DATA *aqh, GWEN_MSG_ENDPOINT *ep, const GWEN_MSG *msg);
+
+
+
+#endif
+
+
+
+
+