nixos-install: Don't pass --show-trace by default
nixos-install: Run in a private mount namespace

This ensures that all mounts are automatically cleaned up.
nixos-install: Assume the build user group is "nixbld"

The build user group is always "nixbld", so no need to detect it.
nixos-install: Don't copy the bootstrap Nix if it's already there

This makes re-running nixos-install a bit faster.
nixos-install: Ask the user to set a root password

This removes the need to have an initially empty root password.
nixos-install: Add operation --chroot

"nixos-install --chroot" runs a command (by default a login shell) in
a chroot inside the NixOS installation in /mnt. This might useful for
poking around a new installation.
nixos-install: Don't bind-mount all of /etc

We only need a copy of /etc/resolv.conf for networking, and
/etc/{passwd,group} for building.
/var/run -> /run
cantata: create version 1.3.4
Allow for later binding in ghcPrefs

Now that both self and super are available to prefFun, we can use self, where appropriate to access late bound versions of most
packages.

When extensions are not used, there is no difference between self and super.
nixos-install: Run in a separate UTS namespace

This prevents the activation script from clobbering our hostname.
nixos-container: Ensure umask 022

Fixes #2585.
jquery-ui: Update to 1.10.4
nixpkgs: Bump libvirt to 1.2.4
rsyncd: default read/write permissions should be nobody:nogroup
Make geoip buildable on any Unix
Add potrace-1.11, a tool for tracing bitmaps
Merge pull request #2583 from CodeBlock/update-httpie

httpie: Update -> 0.8.0
Merge pull request #2506 from ikervagyok/mutt

Updated to mutt-1.5.23
Merge pull request #2454 from MarcWeber/submit/document-composableDerivation

Shea told me composableDerivation is hard to understand.