Move private structures into TransTable

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I noticed there was a comment in the code that originally said:

    // Not clear to me why I can't put the following structs in		
    // the private part of the class as well.  But for some reason		
    // compilation fails then.

I wouldn't be sure why it wouldn't work either...and in fact, I moved it in and it did compile.  So as a sample of starting a discussion in issues and pull requests (vs email) I thought I'd send this as a pull request.  You can add comments here, and we could have a feedback loop which would add more commits to this branch (that I called `private-struct-transtable`) if they were needed.

For now, this branch only exists in **hostilefork/dds** (and on my local machine which is where I pushed it from).  Ultimately what would happen is that these would be either rejected or accepted and pulled into the **dds-bridge/dds** repository.  If you wanted to, you could pull them into **sorenhein/dds** to work with yourself.