message: Add public datatype mod containing ByteOrder
diff: @@ -45,6 +45,10 @@ mod export {
  pub use crate::hl::plist::dataset_access::*;
  }
  + pub mod datatype {
  + pub use crate::hl::datatype::{ByteOrder, Conversion, Datatype};
  + }
  +
  pub mod file {
  pub use crate::hl::file::{File, FileBuilder, OpenMode};
  pub use crate::hl::plist::file_access::*;
  