Added ValueBuffer implementation and simple recording

ValueBuffer is now the default buffer object for storing data for
recording and processing purposes, a simple recording implementation has
been done, core.py example starts recording as soon as the core has
started then on exit it saves the output as a csv file through the
ValueBuffer export_csv method

test/manual/core.py

@@ -19,6 +19,7 @@ config = CoreConfig(port=8765)
 log.info("Configured manual core on %s", config.bind_str())
 dl_core = Core(config)
 dl_core.start()
+dl_core.start_recording()
 
 try:
     while True:
@@ -27,4 +28,5 @@ try:
         log.debug(f"Core values: {values}")
 except KeyboardInterrupt:
     log.info("Received keyboard interrupt")
+    dl_core.stop_recording()
     dl_core.stop()