Programs invoke themselves via `userv' if necessary.

This will prevent the permissions in the key store being messed up.  To
this end:

  * Move `cryptop' to @bindir@ where we can expect users to find it, and
    move `keys' to @sbindir@ where only administrators are likely to
    look.

  * Add a new userv service for `keys', with some configuration files
    listing the permitted users.