Batch processor: Automatic assignment of category to output files

[ubacher]

Addition to the batch processor:

Simplest case: Allow a category to be automatically assigned to the output images.

Elaborate:
Allow assigning/deassigning categories to the input and output images.

Probably also desirable: Allow assigning labels to the output images.
And another possible request: run metadata template on output images.

I think the above capabilities will allow some automation of work flow.