THIS IS ON THE MASTER BRANCH. The Master branch will be Python 3.0 from now on. While Python 2.7 support will not be deliberately broken, all efforts should now focus on Python 3.0 compatibility.
I can see a lot of work has been done. There's more to do. I've bumped the version number of everything I came across to the next major number for Python 3.0 compatibility indication.
Thanks everyone. I hope to update here at least once a week until we have a stable 7.0 release for calibre 5.0
`ebook-convert` converts ebooks without adding them to the calibre library, and so dedrm_tools fails to run and convert books that are processed in this way. Adding on_preprocess means that it will also run on any preprocessing allowing these tools to be used by the cli tools.
As far as I'm aware, there's nothing wrong with having this run in both instances, and it still seems to allow conversion in the "standard way".
