Optimize I/O access (#59)

* Optimize I/O access

A single update() will now fetch information from all interesting modules,
including the current device state and the emeter information.

In practice, this will allow dropping the number of I/O reqs per homeassistant update cycle to 1,
which is paramount at least for bulbs which are very picky about sequential accesses.
This can be further extend to other modules/methods, if needed.

Currently fetched data:
* sysinfo
* realtime, today's and this months emeter stats

New properties:
* emeter_realtime: return the most recent emeter information, update()-version of get_emeter_realtime()
* emeter_today: returning today's energy consumption
* emeter_this_month: same for this month

Other changes:
* Accessing @requires_update properties will cause SmartDeviceException if the device has not ever been update()d
* Fix __repr__ for devices that haven't been updated
* Smartbulb uses now the state data from get_sysinfo instead of separately querying the bulb service
* SmartStrip's state_information no longer lists onsince for separate plugs
* The above mentioned properties are now printed out by cli
* Simplify is_on handling for bulbs

* remove implicit updates, return device responses for actions, update README.md instructions. fixes #61

kasa/smartstrip.py

@@ -146,12 +146,11 @@ class SmartStrip(SmartDevice):
         :return: Strip information dict, keys in user-presentable form.
         :rtype: dict
         """
-        state: Dict[str, Any] = {"LED state": self.led}
-        for plug in self.plugs:
-            if plug.is_on:
-                state["Plug %s on since" % str(plug)] = self.on_since
-
-        return state
+        return {
+            "LED state": self.led,
+            "Childs count": len(self.plugs),
+            "On since": self.on_since,
+        }
 
     async def current_consumption(self) -> float:
         """Get the current power consumption in watts.
@@ -218,6 +217,7 @@ class SmartStrip(SmartDevice):
             plug_emeter_monthly = await plug.get_emeter_monthly(year=year, kwh=kwh)
             for month, value in plug_emeter_monthly:
                 emeter_monthly[month] += value
+
         return emeter_monthly
 
     @requires_update
@@ -245,7 +245,8 @@ class SmartStripPlug(SmartPlug):
 
         self.parent = parent
         self.child_id = child_id
-        self._sys_info = {**self.parent.sys_info, **self._get_child_info()}
+        self._last_update = parent._last_update
+        self._sys_info = parent._sys_info
 
     async def update(self):
         """Override the update to no-op and inform the user."""