Fixes two problems with Substation

1. substation -> sub_station.
2. Substations are usually  buildings (doesn't apply to points unfortunately).

data/presets/presets.json

@@ -2745,7 +2745,8 @@
             "area"
         ],
         "tags": {
-            "power": "substation"
+            "power": "sub_station",
+            "building": "yes"
         },
         "name": "Substation"
     },
@@ -4211,4 +4212,4 @@
         },
         "name": "Weir"
     }
-}
+}

data/presets/presets/power/sub_station.json

@@ -7,7 +7,8 @@
         "area"
     ],
     "tags": {
-        "power": "substation"
+        "building": "*",
+        "power": "sub_station"
     },
     "name": "Substation"
-}
+}