Add download links to ringgo popup

package.json

@@ -74,6 +74,7 @@
         "mapbbcode": "MapBBCode/mapbbcode#v1.2.0",
         "osmtogeojson": "^3.0.0-beta.4",
         "promise-polyfill": "^8.2.0",
+        "togpx": "^0.5.4",
         "topojson-client": "^3.1.0",
         "url-search-params": "~0.5.0",
         "whatwg-fetch": "^3.5.0"
@@ -266,6 +267,11 @@
             "main": [
                 "turf.min.js"
             ]
+        },
+        "togpx": {
+            "main": [
+                "togpx.js"
+            ]
         }
     }
 }