remove crop field from Farmyard preset and add terms (#513)

- Remove landuse=farmland specific field
- Add terms from https://wiki.openstreetmap.org/wiki/Tag:landuse%3Dfarmyard

data/presets/landuse/farmyard.json

@@ -2,8 +2,7 @@
     "icon": "maki-farm",
     "fields": [
         "name",
-        "operator",
-        "crop"
+        "operator"
     ],
     "moreFields": [
         "address",
@@ -18,9 +17,12 @@
         "landuse": "farmyard"
     },
     "terms": [
-        "crop",
-        "grow",
-        "plant"
+        "barnyard",
+        "cattleyard",
+        "feeding",
+        "feedlot",
+        "feedyard",
+        "livestock"
     ],
     "name": "Farmyard"
 }