Navigate between picture previews without swiping effect = slideshow = a computer gallery behaviour

I previously opened an issue for this (#155) but we seemed to have had a little misunderstanding. The idea I tried to present is to have the possibility to toggle a mode with which you don't have to swipe to pass from one picture to the next or previous picture. Maybe some people could like it to function as a slideshow or diaporama, images could just go one after another at regular interval. But for me the really important point is that the images do not move left or right or switch from one to the next with any effect (just like in the third example I give in #155). In this mode, you can play pause image passing. But most importantly (to me ;)) you can pass to the next/previous image with a simple tap on the left or right part of the screen.

This is how I see the UI:

• when viewing an image, tap in the three dot top right menu, you find "slideshow",
• you click on slideshow => the title and other menus disappear,
• you can tap the right or left part of the screen to go to next or previous image,
• to exit this mode, you click the back button which brings you back to the normal image view.

+ this mode could implement lots of gesture shortcuts to trash images (swiping up), like an image (swiping down)... ideally, those gesture shortcuts could even be chosen by the user.

For autoplaying of slideshow, I see two options (that can be combined):

• it's just an option in the app settings, "autoplay in slideshow mode"
• or/and in slideshow mode, if you tap in the middle part of the screen it displays controls (play/pause, next, previous) and you can use those controls to navigate or to trigger playing or pausing of the slideshow. If you wait a few seconds or tap in another part of the screen, the controls disappear.

To me, this feature is THE feature ;) It would be awesomely valuable to select and rate images.

Hope that's a clear and not over detailed explanation. Thanks for the great app, again and again :)