Add resize output option

[TheGameratorT]

Many times I had the case where I just wanted to remove noise on an image without actually resizing it.

Saving images to the disk in very large sizes is not very efficient and it wasted write cycles on my SSD.

I needed to run the model at x2 scale but still save it at x1.

This pull request adds a -r resize option that before writing the output file to the disk, resizes the output in memory if the dimensions of the output don't match what the user specified, thus saving faster and saving disk space.

[Ohrwerk]

I would also find this function very useful, but couldn't it also be realized via an "-S 1"?

[TheGameratorT]

I would also find this function very useful, but couldn't it also be realized via an "-S 1"?

The -s argument does not allow 1 to be specified.