Insurance — Homeowners — All risk policy — Concurrent cause doctrine — Where water damage to insured home was caused by water entering home through walls and windows, an excluded cause, and by water entering through door, a cause which was not excluded, trial court erred in granting directed verdict in favor of insured on basis of concurrent cause doctrine because policy contained an anti-concurrent cause provision — Because evidence of water entering through the walls and windows was undisputed and expressly excluded by policy, entire loss is excluded from coverage due to anti-concurrent cause provision