Fix Crash: Reading canvas tool settings.

Blender would crash when a file was saved where the tool settings is
set to paint on a single image (3d texture painting).

Reason is that the selected image memory address wasn't updated
when the new address.

source/blender/blenkernel/intern/scene.cc

@@ -1173,6 +1173,7 @@ static void scene_blend_read_data(BlendDataReader *reader, ID *id)
       BKE_curveprofile_blend_read(reader, sce->toolsettings->custom_bevel_profile_preset);
     }
 
+    BLO_read_data_address(reader, &sce->toolsettings->paint_mode.canvas_image);
     BLO_read_data_address(reader, &sce->toolsettings->sequencer_tool_settings);
   }