Add maxheight field to parking garage entrance/exit (#232)

Author: cicku

data/presets/amenity/parking_entrance.json

@@ -5,7 +5,8 @@
         "ref",
         "access_simple",
         "address",
-        "level"
+        "level",
+        "maxheight"
     ],
     "geometry": [
         "vertex"