Store/Load cache, show toast with "x new posts ⬆️" on app start

[kojid0]

Every time I restart the app, the cache seems cleared and I get "Your timeline is empty" for a couple of seconds. It would be nice to see the old screen (cache) with a toast on the top saying that there are "x new posts ⬆️" available since I used openbook the last time. With a click on it (or swipe down), it will automatically refresh the "Home" section and bring me to the top with the recent posts.