PTBatcherGUI: reuse intermediate files

PTBatcherGUI: There is an option to always overwrite existing files. Could you add an option to reuse them? When my unstable machine crashes in the middle of an hour of blending it would be nice to have the possibility to skip at least remapping.

When I wrote this on the ptx list, Bruno Postle answered:
> In principle this is possible, the Makefile stitching system can be
> stopped and will restart at the same point (you get this if you
> stitch on the command-line with 'make -f').
>
> I'm not sure how it works with PTBatcherGUI, all the intermediate
> files are created in a temporary location with a randomised name,
> but probably this name is different when you restart, so the
> previously generated intermediate files are unavailable.

There are two sorts of intermediate files: the tiffs made by nona and the tmp files made by enblend. I guess reusing the former would be fairly easy to implement (they are probably what PTBatcherGUI asks about and what I was asking for), the latter might be more difficult, the batch stitcher would at least have to keep track about the temp files and their random names.
But as enblend is the much more time consuming step, this would be of even greater value.