pages/restorable_picker library

1. insta_assets_picker_demo package
2. documentation
3. pages/restorable_picker.dart

insta_assets_picker_demo package

1. Libraries
2. main
3. pages/camera/camera_picker
4. pages/camera/wechat_camera_picker
5. pages/restorable_picker
6. pages/stateless_pickers
7. widgets/crop_result_view
8. widgets/insta_picker_interface