Interface translation by CMake
With a fresh clone, compilation through CMake will currently fail.
Previously, qmake handled auto-generating the language files (.qm files from .ts files) by calling the appropriate Qt tool.
In CMake this might be a bit tricky because apparently it is not the same on all systems. I vaguely remember reading about this not being straight-forward to guarantee it on all systems (at least back then). But maybe this is a non-issue.
Simple solution for now: remove *.qm from gitignore, add it to the repo (after having qmake generate it) and update it manually (or via a simplified qmake file) each time after translating some stuff.
For the future: have CMake find the proper language tool. This would then be as intended, because a dedicated translator could work on the .ts file (with Qt Linguist e. g.) and have nothing to do with compiling.
(Also the README needs updating)