Upgrade VirtualBox Guest Additions to 4.2.6
python-2.6.8: long overdue
fix python-2.6 build: purity for systems with stdenv.gcc.libc

On other systems python26 will continue to look for
/usr/include/netinet/in.h among others. I don't know whether/what to
do about that.
Add preInstall ot buildPythonPackage (postInstall already existed) to allow selenium to work properly again.
haskell-nat: add version 0.3
haskell-naturals: add version 0.2.0.2
haskell-xmonad-extras: update to version 0.11
haskell-active: update to version 0.1.0.3
haskell-diagrams-core: update to version 0.6.0.1
haskell-diagrams-lib: update to version 0.6.0.1
haskell-dual-tree: update to version 0.1.0.1
haskell-lens: update to version 3.7.3
haskell-monoid-extras: update to version 0.2.2.2
haskell-multiarg: update to version 0.8.0.0
haskell-warp: update to version 1.3.7
git-annex: update to version 3.20130107
haskell-type-level-natural-number: add version 1.1.1
haskell-numtype-tf: add version 0.1
haskell-dimensional-tf: add version 0.1.1
firefox: adding 18.0

I had to disable it using some nixpkgs, because they were considered
'too old'. They are simply commented in the code.