Revert "Make py2exe use unbuffered stdin/stdout, which magically makes ssh -W work."

This reverts commit 50c113c302d9b675120860018809eae93d530050.
Revert "Revert "Add code to support using ssh -L when -W is utterly broken.""

This reverts commit e596c48e8fad57451a757b684fbe6ef921ac33cc.