adjust pack-all script to flush status messages
adjust link-all to avoid conflicts
remote-shell: new package for ssh and VirtualBox utilities

Extracted from "meta/pkg-build" and "distro-build".
add meta/test/unix-installer

Drive a virtual machine to test the Unix installer in various
configurations.
remove obsolte build support

Much of the old build support turned into "distro-build" for
package-based builds, and the "build" directory hasn't been
used for a year or so.
remove old web-page sources

The current web pages are in "new-web" (which should probably
change to just "web", eventually).
remove obsolete distribution specs

Replaced by the package system.