tooltip: remove the use of mx_widget_get_border_image
tooltip: remove the use of mx_widget_get_border_image

Border image is no longer an actor, so store a reference to the border
image details and load a texture for it, then paint it when necessary.

jonnylamb/mx,clutter-project/mx,jonnylamb/mx,pwithnall/mx,jonnylamb/mx,clutter-project/mx,pwithnall/mx,clutter-project/mx,pwithnall/mx,clutter-project/mx,pwithnall/mx,jonnylamb/mx