Add field for irrigation=pivot (#1320)

data/fields/irrigation_pivot.json

@@ -0,0 +1,16 @@
+{
+    "key": "irrigation",
+    "type": "defaultCheck",
+    "label": "Center-Pivot Irrigation",
+    "terms": [
+        "central pivot irrigation",
+        "water wheel",
+        "circle irrigation"
+    ],
+    "strings": {
+        "options": {
+            "undefined": "No",
+            "pivot": "Yes"
+        }
+    }
+}

data/presets/landuse/farmland.json

@@ -8,7 +8,8 @@
     ],
     "moreFields": [
         "{@templates/contact}",
-        "address"
+        "address",
+        "irrigation_pivot"
     ],
     "geometry": [
         "area"