Implemented star ratings on all images, as well as color labels rendered as background color of the image tile instead of a round dot.

Implemented toggle buttons which accept keyboard shortcuts. Default shortcuts are not defined, icons on buttons still need some tweaking.

Improved icons on button, fixed tooltips, started working on loading star color from gtkrc.

fixed compile problem :)

reject cross is now drawn properly and working. Stars move one space to the left for the image under the mouse pointer, so that the reject cross has space. Cleaned up button creation in toolbox.

Functionality complete, needs cleanup
All the toggle buttons are working and have proper icons, but there is still a lot of code that needs to be cleaned. Also some display issues need to be fixed for e.g. the fullscreen preview.

Implemented ratings and other toggle buttons
Implemented 5 toggle buttons that allow the user to show various information either for all images or only the active image. This includes ratings, color labels (traditional and background tint style), history label, and reject cross.