chromium: Link against pulse instead of dlopen().

This fixes the issue of Chromium not being able to load the pulseaudio
librarp

We could also propagate the build inputs, but it would end up being the
same as just directoly linking against the library.

Thanks to @aristidb for noticing this in #2421:

https://github.com/NixOS/nixpkgs/pull/2421#issuecomment-42113656

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
chromium: Update all channels to latest versions.

With this commit, the following new upstream versions are introduced:

stable: 34.0.1847.116 -> 34.0.1847.132 (builds fine, tested)
beta:   35.0.1916.47  -> 35.0.1916.86  (builds fine, tested)
dev:    36.0.1941.0   -> 36.0.1964.2   (builds fine, tested)

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
all-packages.nix: strip trailing whitespace
R: added wrapper script that provides "R" and "Rscript" binaries that know about extra libraries

Configure an override in ~/.nixpkgs/config.nix as follows:

  {
    packageOverrides = pkgs: {

      rWrapper = pkgs.rWrapper.override {
        packages = with pkgs.rPackages; [ Defaults dataTable foreach xtable ];
      };

    };
  }
r-packages.nix: added various new libraries