Update Vcs fields

Use the canonical URLs. Rename Vcs-Bzr to Vcs-Git and use the more
efficient git protocol instead of http. Point Vcs-Browser to the
gitweb interface.
French translation : typo fix. Closes: #677272
Update changelog to include Vcs-* changes
debian/gbp.conf: add debian-tag key to ensure git-dch works
* buildlib/apti18n.h.in:
  - fix build failure when building without NLS (closes: #671587)
streamline .gitignore further

adding some comments, regrouping files and use some patterns to avoid
updating the ignore file for new translations or abi changes

Git-Dch: Ignore
build the en manpages in subdirectory doc/en

Building manpages becames more consistent this way and
it is simpler to ignore build artefacts, too.
remove -ldl from cdrom and -lutil from apt-get linkage

Building src:apt shows:
dpkg-shlibdeps: warning: package could avoid a useless dependency if
debian/apt/usr/lib/apt/methods/cdrom was not linked against libdl.so.2
(it uses none of the library's symbols)
dpkg-shlibdeps: warning: package could avoid a useless dependency if
debian/apt/usr/bin/apt-get was not linked against libutil.so.1 (it uses
none of the library's symbols)
rewrite pkgOrderList::DepRemove to stop incorrect immediate setting

Some squeeze → wheezy upgrades indicate that DepRemove runs amok
in complicated setups as it wasn't correctly working with or-groups.
Completely rewritten the check is now moving from or-group to or-group
instead.

The behavior should be the same as the code before, but
(hopefully) with less bugs and more comments.

Closes: 645713