Dallas autosetup (#551)

* Added auto discovery and setup to Dallas Platform

* Added auto discovery and setup to Dallas Platform

components/sensor/dallas.rst

@@ -42,6 +42,23 @@ Configuration variables:
 - **update_interval** (*Optional*, :ref:`config-time`): The interval that the sensors should be checked.
   Defaults to 60 seconds.
 - **id** (*Optional*, :ref:`config-id`): Manually specify the ID used for code generation.
+- **auto_setup_sensors** (*Optional*, boolean): Instruct the hub component to automatically setup and 
+  configure discovered Dallas sensors. See :ref:`dallas-auto_setup_sensors`.
+  Defaults to ``False``
+- **sensor_name_template** (*Optional*, string): Automatically generated sensors will dynamically receive 
+  a ``name`` formatted through this format string ( See c std library ``printf`` for syntax).
+  The internal hub code provides 2 arguments to the printf expression: the node name and the sensor hex address.
+  Defaults to '%s.%s'
+- **resolution** (*Optional*, int): An optional resolution for automatically generated sensors. 
+  Defaults to the maximum for most Dallas temperature sensors: 12.
+- **unit_of_measurement** (*Optional*, string): Manually set the unit
+  of measurement the automatically generated sensor should advertise its values with. This does
+  not actually do any maths (conversion between units).
+  Defaults to '°C'
+- **icon** (*Optional*, icon): Manually set the icon to use for the sensor in the frontend.
+  Defaults to 'mdi:thermometer'
+- **accuracy_decimals** (*Optional*, int): Manually set the accuracy of decimals to use when reporting values.
+  Defaults to 1
 
 .. _dallas-sensor:
 
@@ -144,6 +161,43 @@ You will see the outputted sensor values changing when they're being warmed.
 When you're finished mapping each address to a name, just change the ``Temperature #1``
 to your assigned names and you should be ready.
 
+.. _dallas-auto_setup_sensors:
+
+Automatic Sensors Setup
+***********************
+
+You would normally setup your sensors by explicitly declaring them with their `address`
+according to the :ref:`dallas-sensor` section. This way you have to know the
+specific sensor address to configure beforehand (or by using the debug log exposed by the 
+`dallas` hub - See :ref:`dallas-getting-ids`). The option to use the sensor `index` too 
+is not reliable as stated in the section.
+With automatic sensor setup instead you will not need any address information beforehand since
+the dallas hub component will automatically instantiate every sensor attached to the bus during 
+the initial discovery process. This way you can attach any sensor to the bus and see it inside 
+the fontend as soon as the node initializes itself (during boot then - no hot-plug here!).
+The sensors generated through this model will receive a default setup as configured 
+in :ref:`dallas-component`. The relevant option here is `sensor_name_template` which allows for a
+dynamically generated sensor name according to the format string provided. The formatting function
+receives two string arguments (c code here): the `device_name` of the EspHome node and 
+the hex `address` of the discovered sensor
+
+.. code-block:: yaml
+
+    # Example configuration entry
+    dallas:
+      - pin: GPIO1
+        auto_setup_sensors: true
+        sensor_name_template: '%s.Temperature %s'
+        resolution: 9
+
+This code block example shows how to provide a basic configuration. Every sensor here will
+be set to a 9 bit resolution and the name following the example would be something like
+'my_awesome_node.Temperature BE0316838979FF28'.
+Automatically detected sensors will not conflict with static ones configured in 
+:ref:`Sensor <dallas-sensor>`. If during initialization any sensor address matches a 
+configured one through :ref:`Sensor <dallas-sensor>` the latter configuration will prevail. This way
+you can still provide custom settings (i.e. filters or so) for very specific sensors.
+
 See Also
 --------