Test maximum message sizes

[kroezone]

With new embedding changes, there is a risk that some of the large composite objects could have a message size that exceeds the maximum, which would cause many nasty problems

We need to validate the maximum encoding size for every object type.

Suggested strategy:

• Create sample objects of maximum size
• Create static final constants listing the expected maximum size
• Ensure sample object equal expected maximum
• Add tests for invariants relating size of composite objects to size of embedded objects