Remove unused imports
buildpackage: use get_commit_info() instead of get_subject()

Utilize the get_commit_info() method of GitRepository instead of the
deprecated get_subject().

Signed-off-by: Markus Lehtonen <markus.lehtonen@linux.intel.com>
GitRepository.get_subject: use get_commit_info

This kills another _git_getoutput. Also deprecate the method since we
don't need to special case the subject.
Simplify expression

Git-Dch: Ignore
GitRepository/diff: allow single object

Allow diffing a single object, e.g. getting diff from single commit.

Signed-off-by: Markus Lehtonen <markus.lehtonen@linux.intel.com>
Add wrapper for all gbp commands

So like git you can now use gbp <command> instead of git-<command> or
gbp-<command>. The manpages and docs aren't adjusted yet.
GbpOptionParser: Make sure we access the GbpOptionParser*'s default dict

and not the one from the OptionParser. The instance's default dict this
gets reset to empty when invoking OptionParser.__init__.
GbpOptionParser: Make sure we parse the old config sections

For backward compatibility between {gbp,git}-<subcommand> and "gbp
<subcommand>" make sure we parse the former sections if using the later.
GbpOptionParser: add test for 'filter' option handling
Git-Ignore generated gbp.conf.5 too
Bash complete on "gbp <command>" too
Add gbp manpage
docs: Use gbp <command> instead of {git,gbp}-<command>
manpages: Changes references from git- to gbp-
docs: Rename the entities from &git-<command>; to &gbp-<command>;
gbp.conf: Use command names instead of {git,gbp}-
Rename the sgml files from git- to gbp-
NEWS: add a note about the new gbp super command
Update package description
gbp: support --help