The current official Qt version is 5.3.1. This means all major distributions should have had more than enough time to move to Qt5. Time to drop any Qt4 support.
Version 0071 is an 'early' version. When I started to do more than adjusting the CMakeLists.txt file for Qt5, I discovered some ugly bugs. Initially I just wanted to improve some looks, add an optional menubar, and add some help functionality. However, the fixed bugs... one very ugly (and stupid) in the threading code, one in the database, which made the image rename function hard to use, made me release this early version.
The bugs are gone, but help and menubar is not 100% implemented, yet. Some widgets already look a bit nicer. Still not what I have in mind, but they are now done with the Qt Designer. This does not guarantee nicer widget, but makes them easier to change in the future.