Come back and graphical installer

[Mathieu Othacehe]

Hi Guix !

First mail since a while ! I'm currently finishing a long bicycle trip,
and was able to start hacking again.

I picked up the "Graphical installer" task. After studying the branch
wip-installer-2, I choose to rewrite it for multiple reasons:

* I found the guile-ncurses approach too low level and think that many
  bugs in the current installer could be avoided with a higher level
  library.
* As suggested by Ludo[1], using a network manager seems to be a better
  idea that calling iw, ip and other low level tools.
* I prefer relying on a Guile-parted library rather than calling cfdisk
  and again interfacing with various partioning tools.

While a lot of work have been accomplished by John and Danny, fixing the
above issues mean rewrite it almost completely anyway.

So, I wrote Guile bindings for newt[2], which can be found here[3]. Newt
is the library used by Debian installer and the Anaconda installer
(RedHat, Centos, ...).

I choose to interface with Connman via connmanctl. It would have been
better to use DBus but it implies writing Guile-dbus and I did not have
the courage.

Based on this, I have a first draft for a new installer here[4]. I plan
to push it on a wip savannah branch soon. Most of the basic features are
implemented and the last missing part it the partioning one (also the
bigger ...).

I will soon share some iso files to have some feedbacks. Even if it
might be too late already, I think that releasing the 1.0 with a
graphical installer would be a big plus.

Mathieu

[1]: https://lists.gnu.org/archive/html/guix-devel/2017-01/msg01255.html
[2]: https://en.wikipedia.org/wiki/Newt_(programming_library)
[3]: https://gitlab.com/mothacehe/guile-newt
[4]: https://github.com/mothacehe/guix/tree/installer