* app/gegl/gimpoperationpointlayermode.c
(gimp_operation_point_layer_mode_process): Implemented the layer
modes Hue, Saturation, Color and Value.

Works the same for 100% opaque layers:
 o Hue
 o Saturation
 o Color
 o Value

* libgimpcolor/gimphsl.[ch]: Added gimp_hsl_set().

svn path=/trunk/; revision=27466