add fields for level crossing (#194)

data/fields/crossing/barrier.json

@@ -0,0 +1,16 @@
+{
+    "key": "crossing:barrier",
+    "type": "combo",
+    "label": "Barrier Arm",
+    "strings": {
+        "options": {
+            "full": "Full",
+            "double_half": "Double Half",
+            "half": "Half",
+            "no": "no",
+            "yes": "yes"
+        }
+    },
+    "autoSuggestions": false,
+    "customValues": false
+}

data/fields/crossing/bell.json

@@ -0,0 +1,5 @@
+{
+    "key": "crossing:bell",
+    "type": "check",
+    "label": "Bell"
+}

data/fields/crossing/light.json

@@ -0,0 +1,5 @@
+{
+    "key": "crossing:light",
+    "type": "check",
+    "label": "Lights"
+}