Movie filename in plMovieMsg and plBinkPlayer => plString
pfGameGUIMsg => plString
Clean up DisplaySystemVersion() to avoid hsStrcpy, and add Windows 8.1
to the known versions decoder.
proVariableEventData name => plString
Remove name from hsReaderWriterLock, since nobody was using it.
Clean up plAvatarMsg a bit
pfBackdoorMsg => plString