Nix Packages 0.7

* The bootstrap process for the standard build environment on Linux
  (stdenv-linux) has been improved.  It is no longer dependent in its
  initial bootstrap stages on the system Glibc, GCC, and other tools.
  Rather, Nixpkgs contains a statically linked bash and curl, and uses
  that to download other statically linked tools.  These are then used
  to build a Glibc and dynamically linked versions of all other
  tools.

  This change also makes the bootstrap process faster.  For instance,
  GCC is built only once, not thrice.

  (Contributed by Armijn Hemel.)

* Many packages have been changed and added, but notably:

  - Qt 3 has been added.

  - Mysql has been added.