streamclone: fold in localrepo.storefiles

store: change handling of decoding errors

store: simplify walking - fold in main walking function - eliminate recursion (especially recursive yielding!) - eliminate default args

store: simplify class hierarchy

statichttp: use store class This lets us nix store.encodefn.

store: take opener as an argument

localrepo: simplify requirements checking

localrepo: kill _createmode

add test-verify

verify: check repo.store

revlog: add files method

store.py: accept empty repos Fixes a traceback on the server side when trying to streamclone an empty repo (this was *not* introduced by 80e51429cb9a).