Eliminate vendored sexagesimal library

(re: #3180)

modules/ui/core/feature_list.js

@@ -1,3 +1,5 @@
+import { default as sexagesimal } from 'sexagesimal';
+
 export function FeatureList(context) {
     var geocodeResults;
 

modules/ui/core/rollup.config.js

@@ -0,0 +1,9 @@
+import nodeResolve from 'rollup-plugin-node-resolve';
+import commonjs from 'rollup-plugin-commonjs';
+
+export default {
+    plugins: [
+        nodeResolve({ jsnext: true, main: true }),
+        commonjs()
+    ]
+};