stack: get stack data directly from stack and remove stackdata() stackdata function began its life in 137f8b04901e as a proto-stack: it computed stack revs on its own and only had one property to return, "changesetcount". Later it started to prepare and return more properties, but since b933a8068c17 it was computing revs using a getstack function. And then finally in 17749d9d3968 it started to rely on stack class entirely. It was a good function, but now, when all the logic it provided was factored into stack class, I'd say it's finally time for it to be put to rest.