release.sh: jail install

release.sh: jail install

	. Feature to do a 'release' into a permanent
	  and usable FS hierarchy, usable with chroot
	. Just like the temporary staging hierarchy really
	. Useful to checking out and building the latest
	  version of minix from a host minix; to
	  (1) make an uptodate minix jail, and
	  (2) make a sterile, reproducible jail environment, and
	  (3) use as disposable environment in which moving /usr/pkg
	      is ok
	  (i.e. pkgsrc bulk builds)