Extend multipass

I alleviated some awkardness. Since I created the height readable parameter in [#25](https://github.com/ufo-kit/ufo-filters/pull/25) one can do `ufo-sinos -i foo/ -o bar/ --pass-size 10` (no more `num`).
Also, I can imagine that one wants to make only a subset of sinograms, thus now we have:
`ufo-sinos -i foo -o bar/ --region 100:200:2` which works the same is it did before in `ufo-perf`.