Add web front-end and fix API issues

node_modules/rxjs/dist/esm5/internal/operators/switchScan.js

@@ -0,0 +1,12 @@
+import { switchMap } from './switchMap';
+import { operate } from '../util/lift';
+export function switchScan(accumulator, seed) {
+    return operate(function (source, subscriber) {
+        var state = seed;
+        switchMap(function (value, index) { return accumulator(state, value, index); }, function (_, innerValue) { return ((state = innerValue), innerValue); })(source).subscribe(subscriber);
+        return function () {
+            state = null;
+        };
+    });
+}
+//# sourceMappingURL=switchScan.js.map