nodemap: use bytes for the error message Spotted by Yuya Nishihara.

py3: use native strings when forming email headers in patchbomb Per previous changesets, encoded header's values are native str. We complete the change in patchbomb extension to have literal header values native str as well. Then we can also change headers' keys to be str. In _msgid(), we still need to use encoding.strfromlocal() because usage of os.environ is not allowed by check-code. This finally removes the "if pycompat.ispy3:" TODO.

mail: convert addr to str early in addrlistencode()

mail: let addressencode() / addrlistencode() return native strings Avoids conversion to "str" on py3.

mail: let headencode() return a native string This is to avoid conversion to/from str on py3.

revlog: deprecate direct `nodemap` access Now that all in-core user have been updated to the new API, we can deprecated direct access to nodemap. Differential Revision: https://phab.mercurial-scm.org/D7362

revlog: drop special hack in the `nodemap` property This code does not seems necessary anymore. Differential Revision: https://phab.mercurial-scm.org/D7361

perf: make `perfrevlogindex` use the new `index.rev` api if available Differential Revision: https://phab.mercurial-scm.org/D7360

perf: make `perfnodemap` use the new `index.get_rev` api if available Differential Revision: https://phab.mercurial-scm.org/D7358

index: use `index.get_rev` in `remotefilelog` Differential Revision: https://phab.mercurial-scm.org/D7357