obshistory: add a graph option on the debugobshistory command Add a graph option (--graph) to the debugobshistory. The output is like the 'hg log -G' output. The option is activated by default but can be deactivated with '--no-graph' option. There are various issue with the current implementation (multiple cycles handling, N² complexity) but this can be fixed later.

# name space package to host third party extensions
from __future__ import absolute_import
import pkgutil
__path__ = pkgutil.extend_path(__path__, __name__)