lib/Core
~~~~~~~~

* Add endianness support to the native reader and writer.

* The NativeReader has lots of similar code for converting arrays of ivar
  data in mapped memory into arrays of objects.  The commonality can be
  factored out, maybe templatized.

* The NativeFileFormat.h is old school C structs and constants.  We scope
  things better by defining constants used with a struct inside the struct
  declaration.

* The native reader and writer currently just blast in memory enumeration
  values (e.g. DefinedAtom::Scope) into a byte in the disk format.  To support
  future changes to the enumerations, there should be a translation layer
  to map disk values to in-memory values.