Merged requested to merge Tamaranch/ristretto:device-scale into master
This prevents the image and the thumbnails from being scaled with the rest of the window when a device scale is used. Thus the image is displayed by default in real size (if the size of the view allows it) and the quality of the thumbnails is not altered. It is then up to the user to adjust their size via the settings.
Fixes #47 (closed).