make the multipolygon relation type searchable (#481)

Author: k-yle

data/presets/type/_multipolygon.json data/presets/type/multipolygon.jsondata/presets/type/_multipolygon.json renamed to data/presets/type/multipolygon.json

@@ -1,14 +1,12 @@
 {
     "icon": "iD-multipolygon",
     "geometry": [
-        "area",
         "relation"
     ],
     "tags": {
         "type": "multipolygon"
     },
     "removeTags": {},
     "name": "Multipolygon",
-    "searchable": false,
     "matchScore": 0.1
 }