Control Panel: Better steps and units in paramtree

This should be more intuitive to first-time users, as there is explicit
indication to what the reading values are, corresponding to the plotted
values.

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):

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",
@@ -158,7 +164,7 @@
                "name": "R₀",
                "type": "float",
                "value": 10000,
-               "step": 1,
+               "step": 100,
                "siPrefix": true,
                "suffix": "Ω",
                "compactHeight": false,
@@ -172,7 +178,7 @@
                "name": "B",
                "type": "float",
                "value": 3950,
-               "step": 1,
+               "step": 10,
                "suffix": "K",
                "decimals": 4,
                "compactHeight": false,
@@ -317,7 +323,8 @@
                      "value": 1.5,
                      "step": 0.1,
                      "prefix": "±",
-                     "format": "{value:.4f} °C",
+                     "suffix": "K",
+                     "decimals": 4,
                      "compactHeight": false,
                      "pid_autotune": "temp_swing"
                   },