Gove LockInfo a Marshal method for easy serialization, and a String
method for more readable output.
Have the state.Locker implementations use LockError when possible to
return LockInfo and an error.
This makes it more apparent that the information passed in isn't
required nor will it conform to any standard. There may be call sites
that can't provide good contextual info, and we don't want to count on
that value.
Changed from state.StateLocker to remove the stutter.
State implementations can provide Lock/Unlock methods to lock the state
file. Remote clients can also provide these same methods, which will be
called through remote.State.
James Bardin