Goals for Serialization/Deserialization, implementation approach.

[xenia-foxtrot]

Goals

• Cap'n Proto was designed for extremely memory-efficient de-serialization, which we should utilize in this implementation. Let's avoid unnecessary memory usage and invoking the GC. I would be okay with the usage of unsafe in this layer, provided we have ample testing.
• Compatible with AOT. This is one of the most basic layers of Cap`n Proto. I think it should be usable in all scenarios.