More generally, `LINK_MODE' controls how the `PKGS' value is saved
or restored: "--save" saves the value (the default), "--restore"
uses a previously saved value (if any), and "" disables saving or
restoring.
The `again' target recurs to `in-place' with `LINK_MODE=--restore'.
Also, improve connection between installers and farm-configuration
entries, and improve configuration of installer name versus
target-install directory.
Use `PKGS' with the top-level makefile to select packages for
a development-mode build. The default is "main-distribution",
which includes all packages in "pkgs".
Making them "etc"-relative intercts badly with redirecting
a configuration to override just a few values --- such as
the links path, which is what `make core' needs.
The `farm' target run `server', but after the server starts, also
builds clients (via `ssh') as specified in a configuration file.
A client can be a VirtualBox virtual machine, in which case
the client machine can be started and stopped automatically.
Most of the work is in `distro-build/drive-clients' (in the
"distro-build" package), and that's where the configuration-file
format and client-machine requirements are documented.
The "racket" directory contains a pared-back version of the
repository, roughly.
The "pkgs" directory everything else in the repository, but
organized into packages.
