2006-09-20  Michael Natterer  <mitch@gimp.org>

	* app/core/gimpgradient.[ch]: added gimp_gradient_flatten() which
	creates a copy of a gradient with all colors that refer to FG or
	BG turned into constant colors.

	* app/core/gimpdrawable-blend.c (gradient_fill_region): create a
	flat copy of the gradient if it contains FG/BG colors. Avoids
	gazillions of context color lookups while rendering, depending on
	gradient and blend complexity.