Use 'c' prefix for client, 's' prefix for server, and 'fw' prefix for
firewall messages. The 'c' and 's' prefixes were used sometimes but
not consistently. The firewall printed messages prefixed with
"firewall manager:" or "firewall:" or ">>" previously.

This patch also fixes a couple of print() calls that should have been
debug1()---a bug introduced in a recent commit.