VANCOUVER, Wash., July 30 — (AP) — While the justice of the peace presided at one end of the long distance telephone line, and the offender at the other end stood to acknowledge his guilt, cross-country justice prevailed in southwestern Washington today. In the Columbia national forest Lincoln Mansfield of Portland, was arrested by a forest guard for violating the forest closure rule. The guard, Mike Palidinia, telephoned to Carson, Wash., to reach Justice of the Peace Joe Gregorius. The co