prepare release
Merge remote-tracking branch 'mvo/debian/sid' into debian/sid
releasing package apt version 0.9.15.3
remove auto-generated apt-key and sources.list on clean (closes: 739749)
improve clean for auto-generated sources.list
Fix typos in documentation (codespell)
add apt-vendor information for tanglu
ExtractTar: Allow an empty decompressor program

This allows for uncompressed tar files, as the decompressor process will
not get interposed in-between the file descriptors.
DebFile: Refactor ExtractTarMember() out from ExtractArchive()

Generalize DebFile::ExtractArchive() to take a member base name, so that
we can reuse it for control.tar member extraction too.
Add support for data.tar, control.tar and control.tar.xz

Sync the deb(5) format support with latest dpkg, by allowing
uncompressed tar members and xz compressed control.tar. This
also refactors the control.tar member extraction by using
ExtractTarMember(), which also means future changes only need
to be implemented in a single place.
debian: Add debDebFile::ExtractTarMember to the symbols file
add testcase for Bug#718329
fix ADT failure in downloadfile()
skip test if "apt" is not build
add missing libdb-dev to debian/tests/control
test/integration/test-ubuntu-bug-346386-apt-get-update-paywall: use http-method from METHODSDIR
releasing package apt version 0.9.15.4
vendor/tanglu/makefile: add missing clean/sources.list
Bug#739988: Fix autopkgtest missing dependencies and locale

debian/tests/control: Add missing build-essential, fakeroot, and wget test
dependencies.

debian/tests/run-tests: Pin locale to C to avoid test failures in other
locales.