Added time left for recommended sensor cleaning (#119)

* Added time left for recommended sensor cleaning

Unfortunately I am unable to test these changes, however I believe they should work.

* Remove witespace

Github browser based editor sucks!

* Correct wrong instance name and renamed property

* Correct wrong instance again!

* Update CLI to use new dirty sensor value

miio/vacuum_cli.py

@@ -141,7 +141,8 @@ def consumables(vac: miio.Vacuum):
                                                res.side_brush_left))
     click.echo("Filter:       %s (left %s)" % (res.filter,
                                                res.filter_left))
-    click.echo("Sensor dirty: %s" % res.sensor_dirty)
+    click.echo("Sensor dirty: %s (left %s)" % (res.sensor_dirty,
+                                               res.sensor_dirty_left))
 
 
 @cli.command()

miio/vacuumcontainers.py

@@ -292,6 +292,7 @@ def __init__(self, data: Dict[str, Any]) -> None:
         self.main_brush_total = timedelta(hours=300)
         self.side_brush_total = timedelta(hours=200)
         self.filter_total = timedelta(hours=150)
+        self.sensor_dirty_total = timedelta(hours=30)
 
     @property
     def main_brush(self) -> timedelta:
@@ -321,6 +322,10 @@ def filter_left(self) -> timedelta:
     def sensor_dirty(self) -> timedelta:
         return pretty_seconds(self.data["sensor_dirty_time"])
 
+    @property
+    def sensor_dirty_left(self) -> timedelta:
+        return self.sensor_dirty_total - self.sensor_dirty
+
     def __repr__(self) -> str:
         return "<ConsumableStatus main: %s, side: %s, filter: %s, sensor dirty: %s>" % (  # noqa: E501
             self.main_brush, self.side_brush, self.filter, self.sensor_dirty)