Use a Kolf icon with nice background and shadows
Improve the Kolf icon with a golf ball with hills and the sky in the background as well as the Breeze-typical shadows.
As suggested in T10243: Some KDE applications could use better icons.
Reviewed By: VDG, ndavis
Subscribers: GB_2, ndavis, yurchor, kde-frameworks-devel
Differential Revision: https://phabricator.kde.org/D17969