kvstore: begin rewrite (ErrNotFound ⇔ found bool). mv kvstore kvstore-1
kvstore: rewrite Store and TransStore without ErrNotFound
kvstore: rewrite memkv, Store&TransStore tests
kvstore: rewrite sqlite3kv
kvstore: rewrite postgresqlkv

And fix a recent test-rewrite: the rewrite wasn't correct
kvstore: rewrite mysqlkv
kvstore: rewrite prefix stores
kvstore: rewrite KeyCollection, KeyQueue and their Iterators
minor: kvstore: go fmt
kvstore: end rewrite; rm kvstore-v1/
minor: kvstore: godoc.org lint
serve-git-repos
kvstore: change KeyCollection to not include TransStore

This is in preparation for TypedStores: ther are KeyCollections but are
not TransStores.
kvstore: factor out Transactional interface; tweak test organization
kvstore: require Transactional to see updated data during a transaction
kvstore: TypedStore
kvstore: godoc.org lint
minor: kvstore docs, remove pkg trailing slashes
minor: textproc godoc.org lint
minor: textproc go fmt