Add crossing:whistle field

data/fields/crossing/whistle.json

@@ -0,0 +1,14 @@
+{
+    "key": "crossing:whistle",
+    "type": "combo",
+    "label": "Train Horn",
+    "strings": {
+        "options": {
+            "yes": "Required",
+            "optional": "No Train Horn",
+            "wayside": "Wayside/Stationary Horn"
+        }
+    },
+    "autoSuggestions": false,
+    "customValues": false
+}

data/presets/railway/crossing.json

@@ -7,7 +7,8 @@
         "crossing/light"
     ],
     "moreFields": [
-        "crossing/markings"
+        "crossing/markings",
+        "crossing/whistle"
     ],
     "geometry": [
         "vertex"

data/presets/railway/level_crossing.json

@@ -5,6 +5,9 @@
         "crossing/bell",
         "crossing/light"
     ],
+    "moreFields": [
+        "crossing/whistle"
+    ],
     "geometry": [
         "vertex"
     ],