Remove TrueCrypt support (Closes: #7740).
Adjust documentation to reflect the fact that TrueCrypt was removed.
Remove documentation bits about using the TrueCrypt software.
Add a note about the TrueCrypt removal.
Make GnuPG configuration closer to the best practices one (Closes: #7512).

Thanks to Emma Peel and Kill Your TV for the original patches.

The configuration comes straight from:

  * https://help.riseup.net/en/security/message-security/openpgp/best-practices
  * https://github.com/ioerror/duraconf

... modulo these changes:

  * adjust ca-cert-file's location to match where we ship it; this will be fixed
    later on this branch;
  * have communication with keyservers go through Polipo (and in turn, through
    the Tor SOCKS proxy); this is tracked by #7416.

The only removed since our previous configuration is no-auto-key-locate, as it's
actually the default setting.
Symlink the SKS keyservers pool's certificate from the place where duraconf's recommended GnuPG configuration expects it.

... and remove this delta between our configuration and theirs.
Install hopenpgp-tools (from Jessie).

Also fetch libffi6 from testing, hopenpgp-tools needs it, and it's not
in Wheezy.
Update the GnuPG section of the design doc a bit wrt. the changes brought in this branch.
Merge remote-tracking branch 'origin/devel' into feature/7740-remove-truecrypt

Conflicts:
	features/truecrypt.feature
Remove the TrueCrypt wrapper.
Don't explicitly install the "expect" package: we don't ship the TrueCrypt wrapper anymore.

If something else needs it, it'll pull it via dependencies. `git grep expect --
auto config` is empty, and I don't think any custom .deb of ours uses it either.
Simplify sentence
Shorten introduction

Now that we don't include TrueCrypt and that it is not developed anymore we
don't need to justify why anymore.
Format alternative as tip
Move fact to the top
Rename TrueCrypt as 'Opening TrueCrypt volumes using cryptsetup'

We don't ship TrueCrypt anymore and this was the only section left on this page.
Fix formatting

You need to format full HTML inside <div>
Rephrase

- Use 'you' instead of 'one'
- Reuse the title of the page we link to
- Add DocBook classes
- Indicate on which version TrueCrypt was removed
Fix typo in CSS class name.
Translate the v1.2 release note in french