add leveldb
ninja: move out of pythonPackages

ninja is a build system written in C++ that just happens to use python
to build/install *itself*. It is not a "python package".

After this commit, ninja will be at pkgs.ninja instead of
pkgs.pythonPackages.ninja.
ninja: add description and license
ninja: use version attribute

...to avoid the risk of downloading a different version than the package
name suggests (i.e. on the next version bump).
Merge pull request #521 from bjornfor/ninja

Ninja: some small changes
Merge pull request #520 from dysinger/t/leveldb

Add Google's LevelDB (BSD) to Nix
WIP: eagle: new package

FIXME: it doesn't run! I think I've patched all there is but it errors
out when starting:

  $ ./result/eagle-6.4.0/bin/eagle
  argv[0] (/home/bfo/nixpkgs/result/eagle-6.4.0/bin/eagle) is not the currently executed program version!

  And then it's dead (exit value 4).
--

Eagle is a schematic capture and PCB layout program from CadSoft. This
is proprietary software and CadSoft provide a self-extracting shell
script with embedded tarball of the prebuilt application.

Add Eagle version 6.4.0.