gnu: Move libarchive to (gnu packages backup).

* gnu/packages/compression.scm (libarchive): Move to...
* gnu/packages/backup.scm (libarchive): ... here.
  Import (guix licenses) with #:renamer to avoid conflicting 'zlib'
  bindings.

gnu: Add rdiff-backup.

* gnu/packages/backup.scm (rdiff-backup): New variable.

gnu: Add btar.

* gnu/packages/backup.scm (btar): New variable.

gnu: Add rdup.

* gnu/packages/backup.scm (rdup): New variable.

gnu: Add libarchive.

* gnu/packages/compression.scm (libarchive): New variable.

gnu: Add hdup.

* gnu/packages/backup.scm (hdup): New variable.

gnu: libgnome: Correct source file name.

* gnu/packages/gnome.scm (libgnome): Correct source file name.

gnu: fuse: Allow use of 'fusermount' taken from $PATH.

* gnu/packages/linux.scm (fuse) <set-file-names>: Set FUSERMOUNT_DIR in
  lib/Makefile.

gnu: Add sshfs-fuse.

* gnu/packages/linux.scm (sshfs-fuse): New variable.

gnu: Make gtk-glext depend on pangox-compat and remove workaround patch

* gnu/packages/gnome.scm (gtk-glext): Add new dependency and remove patch
* gnu/packages/patches/gtkglext-remove-pangox-dependency.patch: Delete file
* gnu-system.am: Delete gnu/packages/patches/gtkglext-remove-pangox-dependency.patch

gnu: Add cssc.

* gnu/packages/version-control.scm (cssc): New variable.
* gnu/packages/patches/cssc-gets-undeclared.patch: New file
* gnu/packages/patches/cssc-missing-include.patch: New file
* gnu-system.am: Add gnu/packages/patches/cssc-gets-undeclared.patch
  and gnu/packages/patches/cssc-missing-include.patch

gnu: hdf5: Fix source download location.

* gnu/packages/maths.scm (hdf5): Use "release" directory and not the "current"
    directory for the source, which does not break on new upstream releases.

gnu: Add Autoconf 2.64.

* gnu/packages/autotools.scm (autoconf-2.64): New variable.

gnu: librsync: Fix source uri

* gnu/packages/rsync.scm (librsync) [source]: Fix sourceforge uri.

gnu: Add duplicity.

* gnu/packages/backup.scm: New file.
* gnu-system.am: Add it.

gnu: Add python-mock.

* gnu/packages/python.scm (python-mock): New variable.

gnu: Add python-lockfile.

* gnu/packages/python.scm (python-lockfile): New variable.

gnu: Add Transmission.

* gnu/packages/bittorrent.scm: New file.
* gnu-system.am (GNU_SYSTEM_MODULES): Add it.

gnu: Add gsegrafix and dependent libraries.

* gnu/packages/math.scm (gsegrafix): New variable.
* gnu/packages/gtk.scm (pangox-compat): New variable.
* gnu/packages/gnome.scm (libidl, orbit2, libbonobo, gconf, gnome-mime-data,
  gnome-vfs, libgnome, libart-lgpl, libgnomecanvas, libgnomeui, libglade,
  libgnomeprint, libgnomeprintui, libbonoboui): New variables.

gnu: Add mcrypt, libmcrypt, and libmhash.

* gnu/packages/mcrypt.scm: New file.
* gnu/packages/patches/mhash-keygen-test-segfault.patch: New patch.
* gnu-system.am (GNU_SYSTEM_MODULES): Add file.
  (dist_patch_DATA): Add patch.