Added BlobData API which will serialize as a binary file blob.
> Useful for large data structure
```csharp
class MyBinaryData : BlobData
{
public override void Serialize( ref Writer writer )
{
writer.Stream.Write( 1337 );
}
public override void Deserialize( ref Reader reader )
{
int val = reader.Stream.Read<int>();
}
}
```
