Fixed update of From/To header to include tag

Ignore-this: 981671f23b0fd8b8923135c0c3b07d44

darcs-hash:20090619081054-1e3d8-7435887c814674d2fe054eee88ed75f36aa7860e
Fixed ContactHeader.new to accept FrozenContactHeader

Ignore-this: 2afc066b1ecb998b35e1cbdcbaca8e4e

darcs-hash:20090619153053-1e3d8-ed91c60caad49b21435be41d012397e9237cc9bb