Refactor/ts (#21)

* refactor(ts): add deps

* refactor(ts): add tsconfig

* refactor(rollup): configure ts

src/index.ts

@@ -0,0 +1,14 @@
+import ReactFlow from './container/ReactFlow';
+
+export default ReactFlow;
+
+export { default as Handle } from './components/Handle';
+export { MiniMap, Controls } from './plugins';
+
+export {
+  isNode,
+  isEdge,
+  removeElements,
+  addEdge,
+  getOutgoers
+} from './utils/graph';