wget darwin: disable Test-iri-disabled.px

This test fails on MacOS X. The failure has something to do with
the tests expecting filesystems to accept/store filenames as
bytes. On the HFS+ filesystem, however, filenames are Unicode
characters (Normalisation Form D).

This wget ticket appears to be relevant
    http://savannah.gnu.org/bugs/index.php?27541

The maintainer does not seem to think that this test
failure represents a problem in practice:
    http://article.gmane.org/gmane.comp.web.wget.general/8988

But this patch should be revisited/removed if this aspect of wget is
ever addressed in the future.

NB: I'm also a bit concerned/confused that none of the tests mentioned
in that message seem to fail, so I'm not 100% sure if this is the
relevant issue.
sane: add support for Epson snapscan scanners

The firmware file needs to be downloaded or extracted from the windows
driver file and configured in nixpkgs.config e.g.:

sane.snapscanFirmware = /firmware/esfw41.bin;
sane: tidy-up, wrap expression arguments
xsane: add optional gimp plugin support
gtk2: minor update .20 -> .22
mesa: bugfix update 9.1.6 -> .7

Thist is just for master before the official release,
x-updates has 9.2.* already.
Merge #1082: Update QtCreator to 2.8.1, add Qt 5.1.1 and QtSDK
gimp: upgrade to 2.8.8

This also fixes color management support (lcms2)
polkit: major update 0.105 -> 0.112

- It now uses JavaScript for configuration (only),
  so I had to "convert" config for NetworkManager.
- I tested suspend/restart/(un)mount on KDE/Xfce,
  Phreedom tested NetworkManager config conversion.
nixos/graphite: fix storage dir for carbon
rubyLibs.resque_web: add expression
pythonPackages.mpmath: add expression
libunibreak: meta.platforms attribute
fbreader: add meta.platforms attribute
changes proposed for 13-10 update

One feature change: polkit update 8d14c7ba
linux: Update to 3.11.7
tig: bump 1.1 -> 1.2.1

XML_CATALOG_FILES is needed to be able to build the asciidoc
documentation/manpages in this new version.
tig: small expression cleanup

* Add a bit of whitespace to make it easier on the eyes
* Shorten the description (and remove package name)
subversion: install bash completion
ghc: several enhancements to the new "with-packages" wrapper

 1) The wrapper erroneously used the ghc-pkg flag "--package-db" instead of
    "--global-package-db". The result was that packages installed locally in
    ~/.ghc and ~/.cabal were invisible to GHC. This has been fixed.

 2) The wrapper now deals gracefully with an empty package set: if no package
    is requested to be included in the wrapped environment, the wrapper just
    installs a pristine GHC.

 3) Correctly configure the "docdir" path returned by ghc-paths.

 4) Added some comments that describe the idea behind our ghc-paths patches and
    gives users same sample shell code that can be used to import our special
    environment variables into the currently running shell, so that programs
    outside of the wrapped environment can use them, too.