* Moved some scriptlets to the appropriate modules.
* Put the scriptlet that sets the default path at the start, since it
never makes sense not to have it there. It no longer needs to be
declared as a dependency.
* If a scriptlet has no dependencies, it can be denoted as a plain
string (i.e., `noDepEntry' is not needed anymore).
svn path=/nixos/trunk/; revision=23762
(e.g. --install-grub instead of $NIXOS_INSTALL_GRUB). Also support
some nix-build options (e.g. --show-trace and -j).
svn path=/nixos/branches/modular-nixos/; revision=16560
