Offset coordinates by 0.5 pixels to get consistant results for both image

Offset coordinates by 0.5 pixels to get consistant results for both image

2006-03-21  Anders Carlsson  <andersca@imendio.com>

        * gdk/quartz/gdkdrawable-quartz.c:
        (gdk_quartz_ref_cairo_surface):
        (gdk_quartz_draw_rectangle):
        (gdk_quartz_draw_arc):
        (gdk_quartz_draw_polygon):
        (gdk_quartz_draw_drawable):
        (gdk_quartz_draw_segments):
        (gdk_quartz_draw_lines):
        (gdk_quartz_draw_pixbuf):
        (gdk_quartz_draw_image):
        (_gdk_quartz_drawable_get_context):
        * gdk/quartz/gdkdrawable-quartz.h:
        Offset coordinates by 0.5 pixels to get consistant results for both
        image contexts and screen contexts.