QTranslator - fluxer/katie GitHub Wiki
QTranslator loads only translations in custom format (.tr, generated from .pot and .po), consequently the linguist tools (lrelease, lupdate and lconvert) have been replaced with a custom tool (trc). You can emulate plural forms with no-op translations (QT_TR_NOOP and QT_TR_NOOP_UTF8) and QString::arg(), context can be (ab)used as comment.
For an example of how to extract strings that should be translated to .pot file check the updatetranslations.py script.