Made pkg_add -n less bitchy.
Made -p in pkg_add override "default" package location in pkg_create.
Added concept of "slave" and "master" modes, allowing many different things
to be done to packing lists on the fly. This is really something for
front-end drivers to use, but also something for the more expert user.
rename()'ing files before trying to copy them, thus saving
considerable time when targets and staging area are on same filesystem.
