[GSoC] Full Screen Mode

[Ayan-10]

Tasks

• [x] Detect swipe gestures
• [x] Swipe left to view the previous image
• [x] Swipe right to view the next image
• [x] Swipe up to select the picture (the equivalent of tapping it in non-fullscreen mode) and show the next picture (the picture that follows in the folder view, skipping pictures that have either already been uploaded or ignored).
• [x] Swipe down to immediately mark that picture as "Not for upload" (the equivalent of selecting it then tapping "Mark as not for upload" in non-fullscreen mode), and show the next picture.