S allius/issue134 (#135)

* add polling invertval and method ha_remove()

* add client_mode arg to constructors

- add PollingInvervall

* hide some topics in client mode

- we hide topics in HA by sending an empty register
  MQTT topic during HA auto configuration

* add client_mode value

* update class diagram

* fix modbus close handler

- fix empty call and cleanup que
- add unit test

* don't sent an initial 1710 msg in client mode

* change HA icon for inverter status

* increase test coverage

* accelerate timer tests

app/src/modbus.py

@@ -113,7 +113,7 @@ class Modbus():
         self.__stop_timer()
         self.rsp_handler = None
         self.snd_handler = None
-        while not self.que.empty:
+        while not self.que.empty():
             self.que.get_nowait()
 
     def __del__(self):