Enable tagging unspecific crossing (#837, fixes #834)

Author: matkoniecz

data/presets/highway/_crossing.json

@@ -0,0 +1,25 @@
+{
+    "fields": [
+        "crossing",
+        "tactile_paving",
+        "crossing/island",
+        "crossing/markings",
+        "crossing_raised"
+    ],
+    "moreFields": [
+        "flashing_lights"
+    ],
+    "geometry": [
+        "vertex"
+    ],
+    "tags": {
+        "highway": "crossing"
+    },
+    "matchScore": 0.9,
+    "terms": [
+        "crosswalk",
+        "foot path crossing",
+        "pedestrian crossing"
+    ],
+    "name": "Crossing"
+}