Move the function helper to its own file

Also make it a class so a forward header is generated by syncqt

Change-Id: Ibab6b925dc6e9dab1b617b9b4027a4144e4a3773
Reviewed-by: Timur Pocheptsov <Timur.Pocheptsov@digia.com>
Reviewed-by: Laszlo Agocs <laszlo.agocs@theqtcompany.com>