kes Implement Windows reparse points -- similar to directories, but

kes  Implement Windows reparse points -- similar to directories, but
     we do not descend into it. This is a first cut. They seem to
     be backed up, but restore is not yet tested.
kes  Remove restore_blocking in tls code when shutting a socket to leave
     it in blocking mode. Hopefully this will fix the encryption bug
     reported by Frank Sweetser.
kes  When opening a file for backup, tell the OS that we are going to
     read it sequentially -- optimization.
kes  Change variable names in authenticate_director() to not conflict
     with member names in bat. Caused great confusion with compiler,
     but no warnings.