VMCACHED -- VMcache daemon.

The VMcache daemon is a Unix server which manages a file cache in virtual
memory.  This is used to optimize virtual memory usage, allowing files to
be cached in memory so that they can be shared or accessed without going
to disk.  It is also possible to conditionally access files via "direct
i/o", bypassing system virtual memory and transferring the data directly
from disk to or from process memory.

NOTE: as of Dec 2001, the Vmcache library and vmcached have been updated
to provide the capabilites described above.  The daemon runs, and was used
to develop the VM client interface, which is currently functional, tested,
and installed in os$zfiobf.c.  The new version of the VMcache library
however, has not yet been fully tested and should not be used.

Since this code is still under development it is not part of the normal
IRAF build (hence no mkpkg or mkpkg.sh).