manifest: define and implement addgroup() on manifestlog
Changegroup code was bypassing our manifest interface and calling a
method on the private revlog attribute.
This commit formalizes the interface for adding a group of
revisions from deltas and changes the changegroup code to use it.
This enables alternate manifest storage to work with changegroup
application operations (like `hg unbundle` and `hg pull`).
Differential Revision: https://phab.mercurial-scm.org/D3883
Mercurial
=========
Mercurial is a fast, easy to use, distributed revision control tool
for software developers.
Basic install::
$ make # see install targets
$ make install # do a system-wide install
$ hg debuginstall # sanity-check setup
$ hg # see help
Running without installing::
$ make local # build for inplace usage
$ ./hg --version # should show the latest version
See https://mercurial-scm.org/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.