Add start_date universal field

(re: #3439)

data/presets.yaml

@@ -1136,6 +1136,9 @@ en:
       stars:
         # stars=*
         label: Stars
+      start_date:
+        # start_date=*
+        label: Start Date
       step_count:
         # step_count=*
         label: Number of Steps

data/presets/fields.json

@@ -1527,6 +1527,12 @@
             "type": "number",
             "label": "Stars"
         },
+        "start_date": {
+            "key": "start_date",
+            "type": "text",
+            "universal": true,
+            "label": "Start Date"
+        },
         "step_count": {
             "key": "step_count",
             "type": "number",

data/presets/fields/start_date.json

@@ -0,0 +1,6 @@
+{
+    "key": "start_date",
+    "type": "text",
+    "universal": true,
+    "label": "Start Date"
+}

dist/locales/en.json

@@ -1686,6 +1686,9 @@
                 "stars": {
                     "label": "Stars"
                 },
+                "start_date": {
+                    "label": "Start Date"
+                },
                 "step_count": {
                     "label": "Number of Steps"
                 },