2002-02-19  Michael Natterer  <mitch@gimp.org>

	Fixed #10466 (disappearing pixels when rotating by 90 deg):

	* app/core/gimpdrawable-transform.c: when transforming backwards
	to find the destination line's sub-pixel source coordinates, we
	need to transform the pixels _center_, not it's upper left corner.

	* app/core/gimpdrawable-transform-utils.[ch]: added
	gimp_drawable_transform_matrix_rotate_center() which takes double
	center coordinates instead of an integer pixel bounding box.

	* app/tools/gimptransformtool.[ch]: use double instead of int for
	all coordinates except the original bounding box.

	* app/tools/gimprotatetool.c: use double whenever touching the
	"center" value, so it can be sub-pixel positioned.