server/scm/utils.scm: Fix a comment.
server/scmapi.c: Remove deprecated SCM_STRINGP macro calls.

* server/scmapi.c (scm_send_msg, scm_add_host, scm_update_host):
  Replace deprecated SCM_STRINGP with scm_is_string.
lazycatd.scm: Handle the "stop" command in lazycat-stop procedure.

* server/scm/lazycatd.scm: Handle the "stop" command in
  lazycat-stop procedure.
  (lazycat-stop): Close the server socket.
  (open-socket): Delete old socket file if it exists.