* gnu/packages/version-control.scm, gnu/packages/vim.scm,
gnu/system.scm, gnu/system/dmd.scm, gnu/system/shadow.scm,
gnu/system/vm.scm: Change references to (gnu packages system) to (gnu
packages admin).
This is a followup to commit 4aeea89.
* gnu/system.scm (etc-directory): Add 'locale' and 'timezone'
parameters. Set 'LC_ALL', 'TZ', and 'TZDIR' in /etc/profile.
(operating-system-derivation): Adjust call accordingly.
* gnu/system/vm.scm (%demo-operating-system): Change locale to
'en_US.UTF-8'. Add TZDATA to 'packages'.
* gnu/system.scm (union): Allow (PACKAGE OUTPUT), (PACKAGE), and
PACKAGE.
(<operating-system>)[packages]: Make the default a list of package?
objects.
* gnu/system/vm.scm (%demo-operating-system): Likewise. Add a few
packages.
* gnu/system/shadow.scm (<user-account>)[inputs]: New field.
(passwd-file): Bind the 'shell' field of each account.
* gnu/system/vm.scm (%demo-operating-system): Remove 'shell' field.
* gnu/system/dmd.scm (guix-build-accounts): Store a monadic value in
'shell'. Add 'inputs' field.
* gnu/system.scm (operating-system-derivation): Remove 'shell' field for
'root' account. Add all the 'user-account-inputs' to EXTRAS.
* gnu/system/vm.scm (lower-inputs): Move to monads.scm.
(qemu-image): Don't add GRUB-CONFIGURATION to the INPUTS-TO-COPY.
(union, file-union, etc-directory): Move to gnu/system.scm.
(%demo-operating-system): New variable.
(system-qemu-image): Add 'os' parameter. Rewrite in terms of
'operating-system-derivation'.
* guix/monads.scm (lower-inputs): New procedure.
* gnu/system/grub.scm (grub-configuration-file): Change 'entries' to be
a plain list instead of a list of monadic values.
* gnu/system.scm: New file.
* gnu-system.am (GNU_SYSTEM_MODULES): Add it.
