Remove z88dk nonfree files

See http://www.z88dk.org/forum/viewtopic.php?pid=8504. The package z88dk was blacklisted, but the files with noncommercial restrictions are not required (test suite and keyboard driver), so I made a package helper to remove those files. Requires trisquel/ubuntu-purge!11.

See merge request !49

README -> README.md

Since these repositories are hosted on `gitlab` I thought it was nice to have the `README` in markdown format.

See merge request !48

Add make-tcltrf helper

This helper replaces the nonfree code for the RIPEMD hashing algorithm with free code that I wrote and was included in Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=751879.

See merge request !47

Fix copyright file for grace

The copyright file of grace was taken from labplot, a completely different package. The only thing in common is the cephes library. I replaced the copyright file with the correct one from the Debian grace package.

See merge request !46

Update grace copyright

Closes FSDG https://trisquel.info/en/issues/12192

See merge request !44

Remove nvclock

Removed in ubuntu-purge/master:46110

See merge request !43

The package is no longer useful

Bugfix aptitude

Update ubuntu's patch so it works with Trisquel

Fixes http://trisquel.info/en/issues/13044

See merge request !39

postgresql branding issue

Closes http://trisquel.info/en/issues/13149

See merge request !40

Lighttpd: fix ubuntu references in index.html

Lighttpd currently comes directly from Ubuntu and the default index.html file refers to Ubuntu. This is the page you see if you install Lighttpd and browse to localhost:80. I changed the strings to say Trisquel GNU/Linux but it does refer to "upstream bug tracker" for bugs (i.e. ubuntu launchpad) because Trisquel doesn't list any lighttpd bugs.

See merge request !31

Add Tox (http://tox.im) packages

Tox is a decentralized distributed (no servers) instant messaging app with built-in encryption, audio/video support, file sharing, group chat and more. So far there has been no way to install the various Tox client applications on ubuntu or Trisquel without compiling from source or using a PPA. Although in development and some features aren't complete, they are already usable and useful.

Order of dependencies:

1

- filteraudio, dependency library of qTox
- libsodium, dependency library of toxcore

2

- toxcore, dependency of all Tox clients below

3

- Toxic (ncurses terminal client)
- uTox  (lightweight GUI client using libx11)
- qTox  (GUI client using Qt)

See merge request !32