and get the shell from gimp_canvas_item_get_shell() if needed. Remove
some cairo_translate() that didn't have any effect and were leftovers
from a very early canvas item code.
This is a gross hack that typedefs around between GdkRegion and
cairo_region_t and has some evil #ifdefs. This is going to die
immeditately once we can depend on cairo 1.10.
Add a transform matrix to GimpCanvasBoundary and get rid of the whole
BoundSeg transform code in boundary.c and gimpbrushcore.c, it was
impossible to get this right on that level. Also fix te extents of
GimpCanvasBoundary os it leaves no artifacts.
- GimpCanvasBoundary takes unsorted BoundSeg arrays now and uses
gimp_display_shell_transform_boundary() and gimp_cairo_add_boundary().
- Nobody calls boundary_sort() any longer for the purpose of displaying
a boundary.
- gimp_display_shell_transform_boundary() got offset parameters
so it can transform things that are not in the image's coordinate
system.
