Allow to put cut edge as spine

[fperdigon]

Hey guys amazing work. You saved me the trouble of doing this my self, probably in Python since is the language I am more familiar with.
Maybe I am missing this out, but it will be nice to allow putting cut edge as the spine.
This could be easily archived by rotating all the pages by 180 degrees. In the source manipulation portion.

Best

[momijizukamori]

To be clear, are you thinking of the style used in old Japanese or Chinese books, where each page is sort of a 'pocket' with the fold at the outer edge and the inside of the pocket blank? Best photo I could find quickly, though the bleed is bad enough that the inside almost looks printed too:

We do have #11 open but it's been kind of low priority because I think I'm the only one of the devs that does stab-binding and there hasn't really been requests for the functionality previously