allow randomized seeds in prompt_matrix

[DavidVorick]

I found it useful to keep randomizing the seed when building a prompt_matrix - it allows you to create a much higher diversity of content and can make some very interesting image grids.

[AUTOMATIC1111]

            base = p.seed
            p.seed = []
            for i in range(len(all_prompts)):
                p.seed.append(base+1)

This does not do what you think it does.

[DavidVorick]

Thanks for the merge!

fwiw I did test it locally and it seemed to do what I wanted, but I'm happy to assume there's something I wasn't understanding. Thanks for fixing it up