Move Q_DECLARE_TR_FUNCTIONS into a smaller header

When you have a class which contains string to translate, you have currently 4 choice:

• Use QObject::tr =>bad to maintain tr files
• Use QCoreApplication::translate => passing the class name as string is bad for refactorings
• Inherit by QObject => a moc file will be generated, even it doesn't contain anything required and QObject doesn't have a copy constructor
• Use Q_DECLARE_TR_FUNCTIONS => sounds nice, but your header are getting bloated with unnecessary includes

How it could be solved:

• Simple class which use a forward declaration for QString and the implementation is within a cpp file (QObject then should inherit from this tiny class)
• Move Q_DECLARE_TR_FUNCTIONS to a separate header and move the call QCoreApplication::translate to a cpp file