Add tests for weird port numbers.
Add tests for weird port numbers.

--- FAIL: TestResolveAddr (0.00 seconds)
        pt_test.go:221: "1.2.3.4:http" unexpectedly succeeded: "1.2.3.4:80"
        pt_test.go:221: "1.2.3.4:65536" unexpectedly succeeded: "1.2.3.4:0"

Yawning/goptlib,wyuelin/mygoptlib