Add hook_delete_revision()

that patch no longer applies. i'll re-roll it though, i'd really like to get this in before the code freeze.

whoops, yeah that would have been helpful. oh well, it totally missed the code freeze.

Here's a re-roll for HEAD, the book module now does everything through hook_nodeapi so I won't change it.

moshe, it's both that and just making it obvious to developers how to support revisions. when i originally updated the example node module to support revisions it wasn't obvious to me why i needed to implement hook_nodeapi just for revisions. in my opinion a module should need to implement hook_nodeapi to do anything with its own nodes.

here's a re-roll that applies cleanly.

Dries, i don't know what more i can say that i haven't already said so i'll just summarize.

if you believe that modules should support revisions for nodes then it seems like you'd want to make that as easy as possible. it seems very counter intuitive that to correctly implement revision a module needs to implement hook_nodeapi. in my opinion a module should be able to do so by implementing hook_delete_revision rather than implementing hook_nodeapi to work with it's own nodes.

we've lived for two release without it so it's obviously not critical, but if we really care so much about having clean APIs, it would seem like we could clean up the warts in the ones we've got. if you don't think it's a worthwhile change feel free to mark it as won't fix.