Add web front-end and fix API issues

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

@@ -0,0 +1,12 @@
+import { operate } from '../util/lift';
+import { mergeInternals } from './mergeInternals';
+export function mergeScan(accumulator, seed, concurrent) {
+    if (concurrent === void 0) { concurrent = Infinity; }
+    return operate(function (source, subscriber) {
+        var state = seed;
+        return mergeInternals(source, subscriber, function (value, index) { return accumulator(state, value, index); }, concurrent, function (value) {
+            state = value;
+        }, false, undefined, function () { return (state = null); });
+    });
+}
+//# sourceMappingURL=mergeScan.js.map