bundle: introduce per-engine compression level
If experimental.bundlecomplevel.$engine is set, prefer it over the
generic experimental.bundlecomplevel. Given that compression levels have
widely different meanings across engines, this allows much saner
configuration.
Differential Revision: https://phab.mercurial-scm.org/D3393
bundlespec: drop externalnames flag
Always provide the human readable version of compression and version.
Add the translated wire format name in the new wirecompression and
wireversion fields.
Differential Revision: https://phab.mercurial-scm.org/D3392
revlog: make shortest() take a full binary nodeid (API)
Follow-up to
7b2955624777 (scmutil: make shortesthexnodeidprefix()
take a full binary nodeid, 2018-04-14).
Differential Revision: https://phab.mercurial-scm.org/D3403