Improve printing of SSH keys.

* src/key-type.c (print_key): New procedure.
  (init_key_type): Register the callback for printing.
  (guile_ssh_key_get_type): Use `ssh_privatekey_type' instead of
  `ssh_key_type'.
Merge branch 'master' into ssh-server-api

Conflicts:
	ChangeLog
message-func.c (guile_ssh_message_auth_set_methods_x): Improve.

* src/message-func.c (_scm_member_p): New procedure.
  (guile_ssh_message_auth_set_methods_x): Improve.