This change does two things:
* "NixOSizes" environment variables generation. This allows some more
error-checking and opens possibilities for a modular environment
configuration. From now on the most of environment variables are
generated directly by the nix code. Generating sh code that
generates environment variables is left in a few places where
nontrivial access to a local environment state is needed.
* By doing the first change this patch untangles bash from the
environment configuration and makes it trivial to add a support for
other non bash-compatible shells.
Now to the sad part. This change is quite large (and I'm not sure it's
possible to split it) and yet is not quite complete, it needs some
changes to nixpkgs to be perfect.
See !!! comments in modules/config/shells-environment.nix.
Main principle behind this change is "change environment generation
and nothing else". In particular, shell configuration principles stay
exactly the same as before.
Enabling udisks2 allows gvfs (which should be built with udisks support) to
perform mount/unmount operations on removable drives. It affects Thunar and
probably other Gtk-based file managers.
Gvfs doesn't supports earlier versions of udisks.
enabled by modules that need it (KDE < 4.7, Xfce).
* Don't enable the PolicyKit module by default either, it's also
obsolete (replaced by PolKit). It's still enabled if HAL is
enabled.
svn path=/nixos/trunk/; revision=27933
