For building this application, Qt 5 is required
You can get it here: https://www.qt.io/download/
First build TrackYourTime.pro with Qt Creator - it is a typical Qt project
After building do the following:
Place TrackYourTime.exe in build folder, copy data folder,
copy platforms plugin with qwindows, copy necessary qt libs
Pack in compressed folder TrackYourTime_Windows.zip
Copy data into TrackYourTime.app/Contents/MacOS
add key LSUIElement with value 1 into TrackYourTime.app/Contents/Info.plist
execute macdeployqt with -dmg flag(<path_to_qt/macdeployqt TrackYourTime.app -dmg>)
Rename package to TrackYourTime_MacOSX.dmg
Place TrackYourTime in build folder, copy data folder, copy checksystem Pack into TrackYourTime_Linux.tar.gz
its possible to make this work from console without QtCreator.
But QtCreator is simple and powerfull tool and i prefer to use it.
Open project in QtCreator
Go to menu Tools->External->Linguist->Update Translations(lupdate)
Launch Qt Linguist(<qt_path/bin/linguist>)
Open *.ts file for edit
Edit file(edit item and press Ctrl+Enter)
Save file
Go to menu Tools->External->Linguist->Release Translations(lrelease)
Move *.qm file into data/languages
If you create new language - create file with name data/languages/lang_<lang_id>_name.utf8
Open this file in utf8 text editor
And place only one line in utd8 encoding - name of language in native format