svn merge ^/nixpkgs/trunk

Merge conflicts:
* unzip (almost trivial)
* dvswitch (trivial)
* gmp (copied result of `git merge`)

The last item introduced gmp-5.0.3, thus full rebuild.
+ensureDir->mkdir -p in TeX packages was catched by git but not svn.

svn path=/nixpkgs/branches/stdenv-updates/; revision=32091