gnu: guix: Update snapshot.

* gnu/packages/package-management.scm (guix-devel): Update snapshot.
doc: Clarify use of the 'password' field for user accounts.

Suggested by Alex Sassmannshausen <alex.sassmannshausen@gmail.com>.

* doc/guix.texi (Using the Configuration System): Remove 'password'
  field in the example.
  (User Accounts): Clarify use of the 'password' field, with links to
  the libc and Guile manuals.
gnu: Add Tiled.

* gnu/packages/games.scm (tiled): New variable.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>
Add the name of Sou Bunnbu in its original script to 'AUTHORS'.
gnu: linux-libre: Update to 3.17.3

* gnu/packages/linux.scm (linux-libre): Update to version 3.17.3.
doc: Fix Hydra URL.

Reported by John Darrington <john@darrington.wattle.id.au>.

* doc/guix.texi (Packaging Guidelines): Fix hydra.gnu.org URL.
gnu: Add opus-tools

* gnu/packages/xiph.scm (opus-tools): New variable.
gnu: guix: Fix hash of snapshot source.

* gnu/packages/package-management.scm (guix-devel): Fix hash, which was
  wrongfully input in commit a0e59dd.
gnu: ruby: Update to 2.1.5.

* gnu/packages/ruby.scm (ruby): Update to version 2.1.5.
gnu: hello: Update to 2.10.

* gnu/packages/base.scm (hello): Update to 2.10.
doc: Document "guix import".

* doc/guix.texi (Requirements): Add xref to "Invoking guix import".
  (Defining Packages): Likewise.  Remove footnote about Nixpkgs
  imports.
  (Invoking guix import): New section.
Adjust NEWS for 'guix import'.
doc: Document --key-download option of 'guix refresh'.

* doc/guix.texi (Invoking guix refresh): Document --key-download.
Fix typo in NEWS.
gnu: Add openal.

* gnu/packages/games.scm (openal): New variable.
gnu: Add irrlicht.

* gnu/packages/games.scm (irrlicht): New variable.
gnu: Add minetest-data.

* gnu/packages/games.scm (minetest-data): New variable.
gnu: Add minetest.

* gnu/packages/patches/minetest-subgame-env-var.patch: New file.
* gnu-system.am (dist_patch_DATA): Add it.
* gnu/packages/games.scm (minetest): New variable.
build: Add guix/tests.scm to the distribution.

* Makefile.am (noinst_DATA): Rename to...
  (dist_noinst_DATA): ... this.
build: Add doc/emacs.texi to the distribution.

* doc.am (EXTRA_DIST): Add doc/emacs.texi.