Add module support & query their information during update cycle (#243)

* Add module support & modularize existing query

This creates a base to expose more features on the supported devices.
At the moment, the most visible change is that each update cycle gets information from all available modules:
* Basic system info
* Cloud (new)
* Countdown (new)
* Antitheft (new)
* Schedule (new)
* Time (existing, implements the time/timezone handling)
* Emeter (existing, partially separated from smartdevice)

* Fix imports

* Fix linting

* Use device host instead of alias in module repr

* Add property to list available modules, print them in cli state report

* usage: fix the get_realtime query

* separate usage from schedule to avoid multi-inheritance

* Fix module querying

* Add is_supported property to modules

kasa/modules/usage.py

@@ -0,0 +1,40 @@
+"""Implementation of the usage interface."""
+from datetime import datetime
+
+from .module import Module, merge
+
+
+class Usage(Module):
+    """Baseclass for emeter/usage interfaces."""
+
+    def query(self):
+        """Return the base query."""
+        year = datetime.now().year
+        month = datetime.now().month
+
+        req = self.query_for_command("get_realtime")
+        req = merge(
+            req, self.query_for_command("get_daystat", {"year": year, "month": month})
+        )
+        req = merge(req, self.query_for_command("get_monthstat", {"year": year}))
+        req = merge(req, self.query_for_command("get_next_action"))
+
+        return req
+
+    async def get_daystat(self, year, month):
+        """Return stats for the current day."""
+        if year is None:
+            year = datetime.now().year
+        if month is None:
+            month = datetime.now().month
+        return await self.call("get_daystat", {"year": year, "month": month})
+
+    async def get_monthstat(self, year):
+        """Return stats for the current month."""
+        if year is None:
+            year = datetime.now().year
+        return await self.call("get_monthstat", {"year": year})
+
+    async def erase_stats(self):
+        """Erase all stats."""
+        return await self.call("erase_runtime_stat")