Add MessagePackExtendedTypeObject in primitive layer.
Fix typo/spacing
Fix wrong method name.
Add MPETO tests.
Add ToString() to MPETO
Fix MPETO.ToString()
Add MPETO support to MPO.
Fix doc comment.
Update specs.
Implements Packer.
Implement IPackable.
Implement Ext Unpacking.
Pack<T> now uses SerializationContext.Default.
Fix test.
Move PackerTest.
Fix unpacker ext unpacking bug.
Implement Unpacking class to enable unpack str/bin/ext.
Implement that SerializationContext awares PackerCompatibilityOptions.
Add ext type serializer.
Update built serializers that they respect bin types.