move things that are obviously not gui related into the comon.pri file
TODO done;
highest downloaded episode;
fix highest watched episode;
split playFile into playFile and playFileImpl, so common things can be done and an impl is a must for each childclass;
fix return value for playFile;
move all variables concering the currently played file into a nowPlaying object;
rename json.progress seconds like in the cpp file;
split the gigantic init function into some separated stuff;