Added GalleryComponent interface and navigation buttons

Author: Yrds

src/GalleryComponent.ts

@@ -0,0 +1,9 @@
+import { Gallery } from './Gallery';
+
+interface GalleryComponent {
+  init(gallery: Gallery): void;
+};
+
+export {
+  GalleryComponent
+}

src/NavigationButtons.ts

@@ -0,0 +1,4 @@
+import { Gallery } from './Gallery';
+import { GalleryComponent } from './GalleryComponent';
+
+

src/index.ts

@@ -1,5 +1,11 @@
 import { Gallery } from './Gallery';
+import { GalleryComponent } from './GalleryComponent';
+
+export default Gallery;
 
 export {
-  Gallery
+  Gallery,
+  GalleryComponent
+  //TODO Thumbnail
+  //
 };