Fixing image tapping

@hakubo @kenkouot @rogatty @nandy-andy @aquilax @mklucsarits  This makes tapping work a bit differently as @hakubo found a few issues today:

1) For galleries changeMediaOnTap is triggered only for tapping on 33%-wide sides of the screen. When center area tapped once, the UI toggles. When twice, there's deouble-tap-to-zoom.
2) For non-galleries tapping triggers deouble-tap-to-zoom and tap-to-toggle-ui everywhere, not only for center area.