Another refactor on roler.
Another refactor on roler.

It's all really simple now I think.

kunthar/pachyderm,klucar/pachyderm,ShengjieLuo/pachyderm,ShengjieLuo/pachyderm,alexdebrie/pachyderm,klucar/pachyderm,sambooo/pachyderm,ShengjieLuo/pachyderm,kunthar/pachyderm,alexdebrie/pachyderm,alexdebrie/pachyderm,sambooo/pachyderm,klucar/pachyderm,sambooo/pachyderm