New features:
* Project v2: new layout of the control branch: toplevel branch of each
project and subproject should have .bzrmeta/scmproj/project.cfg file with
project config. No more separate .scmproj control branch needed.
* Project v2 is now default one. Old projects are still supported in all
operations except ``project-init``, so you can't create old project anymore
with ``project-init`` command.
* Config files for projects v2 have the same format as before, but alts and
subsets are not supported in v2.
* ``project-command`` for project v2 now executes actions for control branch
as well as component branches.
* Support for snapshots:
* ``project-commit`` creates snapshots for main project and all
subprojects.
* ``project-get`` uses snapshot...