Control Panel: Move postfilter into its own group

The postfilter is an aspect of the sampling ADC on the Thermostat, and
not the connected thermistor.

pythermostat/pythermostat/gui/view/ctrl_panel.py

@@ -201,13 +201,13 @@ class CtrlPanel(QObject):
                     "Output Config", "Control Method", "Set Current"
                 ).setValue(settings["i_set"] * 1000)
                 if settings["temperature"] is not None:
-                    self.params[channel].child("Temperature").setValue(
+                    self.params[channel].child("Readings", "Temperature").setValue(
                         settings["temperature"]
                     )
                     if settings["tec_i"] is not None:
-                        self.params[channel].child("Current through TEC").setValue(
-                            settings["tec_i"] * 1000
-                        )
+                        self.params[channel].child(
+                            "Readings", "Current through TEC"
+                        ).setValue(settings["tec_i"] * 1000)
 
     @pyqtSlot(list)
     def update_thermistor(self, sh_data):
@@ -244,7 +244,7 @@ class CtrlPanel(QObject):
         for postfilter_params in postfilter_data:
             channel = postfilter_params["channel"]
             with QSignalBlocker(self.params[channel]):
-                self.params[channel].child("ADC Config", "Postfilter Rate").setValue(
+                self.params[channel].child("Postfilter Config", "Rate").setValue(
                     postfilter_params["rate"]
                 )
 

pythermostat/pythermostat/gui/view/param_tree.json

@@ -1,17 +1,23 @@
 {
    "ctrl_panel": [
       {
-         "name": "Temperature",
-         "type": "float",
-         "format": "{value:.4f} °C",
-         "readonly": true
-      },
-      {
-         "name": "Current through TEC",
-         "type": "float",
-         "suffix": "mA",
-         "decimals": 6,
-         "readonly": true
+         "name": "Readings",
+         "type": "group",
+         "children": [
+            {
+               "name": "Temperature",
+               "type": "float",
+               "format": "{value:.4f} °C",
+               "readonly": true
+            },
+            {
+               "name": "Current through TEC",
+               "type": "float",
+               "suffix": "mA",
+               "decimals": 6,
+               "readonly": true
+            }
+         ]
       },
       {
          "name": "Output Config",
@@ -185,11 +191,11 @@
          ]
       },
       {
-         "name": "ADC Config",
+         "name": "Postfilter Config",
          "type": "group",
          "children": [
             {
-               "name": "Postfilter Rate",
+               "name": "Rate",
                "type": "list",
                "value": 16.67,
                "thermostat:set_param": {